Istanbul

Originally built by Constantine the Great in the 4th century and later rebuilt by Justinian the Great after the Nika riots in 532, the Hagia Irene is an Eastern Orthodox Church located in the outer courtyard of Topkapı Palace in Istanbul. It is one of the few Byzantine era churches that were never converted into mosques; during the Ottoman period it served as Topkapı's principal armoury.

Originally a church, later a mosque, the 6th-century Hagia Sophia (532–537) by Byzantine emperor Justinian the Great was the largest cathedral in the world for nearly a thousand years, until the completion of the Seville Cathedral (1507) in Spain.

Constantine the Great effectively became the emperor of the whole of the Roman Empire in September 324.[45] Two months later, he laid out the plans for a new, Christian city to replace Byzantium. As the eastern capital of the empire, the city was named Nova Roma; most called it Constantinople, a name that persisted into the 20th century.[46] On 11 May 330, Constantinople was proclaimed the capital of the Roman Empire, which was later permanently divided between the two sons of Theodosius I upon his death on 17 January 395, when the city became the capital of the Eastern Roman (Byzantine) Empire.[47]

The establishment of Constantinople was one of Constantine's most lasting accomplishments, shifting Roman power eastward as the city became a center of Greek culture and Christianity.[47][48] Numerous churches were built across the city, including Hagia Sophia which was built during the reign of Justinian the Great and remained the world's largest cathedral for a thousand years.[49] Constantine also undertook a major renovation and expansion of the Hippodrome of Constantinople; accommodating tens of thousands of spectators, the hippodrome became central to civic life and, in the 5th and 6th centuries, the center of episodes of unrest, including the Nika riots.[50][51] Constantinople's location also ensured its existence would stand the test of time; for many centuries, its walls and seafront protected Europe against invaders from the east and the advance of Islam.[48] During most of the Middle Ages, the latter part of the Byzantine era, Constantinople was the largest and wealthiest city on the European continent and at times the largest in the world.[52][53] Constantinople is generally considered to be the center and the "cradle of Orthodox Christian civilization".[54][55]

Constantinople began to decline continuously after the end of the reign of Basil II in 1025. The Fourth Crusade was diverted from its purpose in 1204, and the city was sacked and pillaged by the crusaders.[56] They established the Latin Empire in place of the Orthodox Byzantine Empire.[57] Hagia Sophia was converted to a Catholic church in 1204. The Byzantine Empire was restored, albeit weakened, in 1261.[58] Constantinople's churches, defenses, and basic services were in disrepair,[59] and its population had dwindled to a hundred thousand from half a million during the 8th century.[lower-alpha 5] After the reconquest of 1261, however, some of the city's monuments were restored, and some, like the two Deesis mosaics in Hagia Sophia and Kariye, were created.[60]

The 6th century Basilica Cistern was built by Justinian the Great.

Various economic and military policies instituted by Andronikos II, such as the reduction of military forces, weakened the empire and left it vulnerable to attack.[61] In the mid-14th-century, the Ottoman Turks began a strategy of gradually taking smaller towns and cities, cutting off Constantinople's supply routes and strangling it slowly.[62] On 29 May 1453, after an eight-week siege (during which the last Roman emperor, Constantine XI, was killed), Sultan Mehmed II "the Conqueror" captured Constantinople and declared it the new capital of the Ottoman Empire. Hours later, the sultan rode to the Hagia Sophia and summoned an imam to proclaim the Islamic creed, converting the grand cathedral into an imperial mosque due to the city's refusal to surrender peacefully.[63] Mehmed declared himself as the new Kayser-i Rûm (the Ottoman Turkish equivalent of the Caesar of Rome) and the Ottoman state was reorganized into an empire.[64][65]

Map of Istanbul in the 16th century by the Ottoman polymath Matrakçı Nasuh

Following the conquest of Constantinople,[lower-alpha 6] Mehmed II immediately set out to revitalize the city. Cognizant that revitalization would fail without the repopulation of the city, Mehmed II welcomed everyone–foreigners, criminals, and runaways– showing extraordinary openness and willingness to incorporate outsiders that came to define Ottoman political culture.[67] He also invited people from all over Europe to his capital, creating a cosmopolitan society that persisted through much of the Ottoman period.[68] Revitalizing Istanbul also required a massive program of restorations, of everything from roads to aqueducts.[69] Like many monarchs before and since, Mehmed II transformed Istanbul's urban landscape with wholesale redevelopment of the city center.[70] There was a huge new palace to rival, if not overshadow, the old one, a new covered market (still standing as the Grand Bazaar), porticoes, pavilions, walkways, as well as more than a dozen new mosques.[69] Mehmed II turned the ramshackle old town into something that looked like an imperial capital.[70]

Social hierarchy was ignored by the rampant plague, which killed the rich and the poor alike in the 16th century.[71] Money could not protect the rich from all the discomforts and harsher sides of Istanbul.[71] Although the Sultan lived at a safe remove from the masses, and the wealthy and poor tended to live side by side, for the most part Istanbul was not zoned as modern cities are.[71] Opulent houses shared the same streets and districts with tiny hovels.[71] Those rich enough to have secluded country properties had a chance of escaping the periodic epidemics of sickness that blighted Istanbul.[71]

View of the Golden Horn and the Seraglio Point from Galata Tower

The Ottoman Dynasty claimed the status of caliphate in 1517, with Constantinople remaining the capital of this last caliphate for four centuries.[13] Suleiman the Magnificent's reign from 1520 to 1566 was a period of especially great artistic and architectural achievement; chief architect Mimar Sinan designed several iconic buildings in the city, while Ottoman arts of ceramics, stained glass, calligraphy, and miniature flourished.[72] The population of Constantinople was 570,000 by the end of the 18th century.[73]

A period of rebellion at the start of the 19th century led to the rise of the progressive Sultan Mahmud II and eventually to the Tanzimat period, which produced political reforms and allowed new technology to be introduced to the city.[74] Bridges across the Golden Horn were constructed during this period,[75] and Constantinople was connected to the rest of the European railway network in the 1880s.[76] Modern facilities, such as a water supply network, electricity, telephones, and trams, were gradually introduced to Constantinople over the following decades, although later than to other European cities.[77] The modernization efforts were not enough to forestall the decline of the Ottoman Empire.[78]

Two aerial photos showing the Golden Horn and the Bosporus, taken from a German zeppelin on 19 March 1918

Sultan Abdul Hamid II was deposed with the Young Turk Revolution in 1908 and the Ottoman Parliament, closed since 14 February 1878, was reopened 30 years later on 23 July 1908, which marked the beginning of the Second Constitutional Era.[79] A series of wars in the early 20th century, such as the Italo-Turkish War (1911–1912) and the Balkan Wars (1912–1913), plagued the ailing empire's capital and resulted in the 1913 Ottoman coup d'état, which brought the regime of the Three Pashas.[80]

The Ottoman Empire joined World War I (1914–1918) on the side of the Central Powers and was ultimately defeated. The deportation of Armenian intellectuals on 24 April 1915 was among the major events which marked the start of the Armenian genocide during WWI.[81] Due to Ottoman and Turkish policies of Turkification and ethnic cleansing, the city's Christian population declined from 450,000 to 240,000 between 1914 and 1927.[82] The Armistice of Mudros was signed on 30 October 1918 and the Allies occupied Constantinople on 13 November 1918. The Ottoman Parliament was dissolved by the Allies on 11 April 1920 and the Ottoman delegation led by Damat Ferid Pasha was forced to sign the Treaty of Sèvres on 10 August 1920.

A view of Bankalar Caddesi (Banks Street) in the late 1920s. Completed in 1892, the Ottoman Bank headquarters is seen at left. In 1995 the Istanbul Stock Exchange moved to İstinye, while numerous Turkish banks have moved to Levent and Maslak.[83]

Following the Turkish War of Independence (1919–1922), the Grand National Assembly of Turkey in Ankara abolished the Sultanate on 1 November 1922, and the last Ottoman Sultan, Mehmed VI, was declared persona non grata. Leaving aboard the British warship HMS Malaya on 17 November 1922, he went into exile and died in Sanremo, Italy, on 16 May 1926. The Treaty of Lausanne was signed on 24 July 1923, and the occupation of Constantinople ended with the departure of the last forces of the Allies from the city on 4 October 1923.[84] Turkish forces of the Ankara government, commanded by Şükrü Naili Pasha (3rd Corps), entered the city with a ceremony on 6 October 1923, which has been marked as the Liberation Day of Istanbul (Turkish: İstanbul'un Kurtuluşu) and is commemorated every year on its anniversary.[84] On 29 October 1923 the Grand National Assembly of Turkey declared the establishment of the Turkish Republic, with Ankara as its capital. Mustafa Kemal Atatürk became the Republic's first President.[85][86]

Istanbul circa 1970

A 1942 wealth tax assessed mainly on non-Muslims led to the transfer or liquidation of many businesses owned by religious minorities.[87] From the late 1940s and early 1950s, Istanbul underwent great structural change, as new public squares, boulevards, and avenues were constructed throughout the city, sometimes at the expense of historical buildings.[88] The population of Istanbul began to rapidly increase in the 1970s, as people from Anatolia migrated to the city to find employment in the many new factories that were built on the outskirts of the sprawling metropolis. This sudden, sharp rise in the city's population caused a large demand for housing, and many previously outlying villages and forests became engulfed into the metropolitan area of Istanbul.[89]

Şile and Kilyos are two seaside resorts on the Black Sea, the body of water which tempers Istanbul's climate.

Istanbul's climate is temperate, and is often described as transitional between the Mediterranean climate typical of the western and southern coasts of Turkey, and the oceanic climate of the northwestern coasts of the country.[93] Much divergence exists in the terminology used to classify the city's climate, however.

The city's summers are warm to hot and moderately dry, with an average daytime temperature of about 27 °C (81 °F), and less than 7 days of precipitation per month. Despite the generally acceptable temperature range, however, mid-summer in Istanbul is considered moderately uncomfortable, due to high dew points and relative humidity.[94] Winters, meanwhile, are cool, quite rainy, and relatively snow-rich for their well-above-freezing temperatures.

Istanbul's precipitation is unevenly distributed, with winter months getting at least twice the level of precipitation of their summerly counterparts. The mode of precipitation also varies by season. Winter precipitation is generally light, persistent and often of mixed precipitation such as rain-snow mixes and graupel; while summer precipitation is generally abrupt and sporadic. Cloudiness, as with precipitation, varies greatly by season. Winters are quite cloudy, with around 20 percent of days being sunny or partly cloudy. Meanwhile, summers experience 60-70 percent of possible sunshine.

Snowfall is sporadic, but accumulates every winter; and when it does, it is often persistent and disruptive. Sea-effect snowstorms with more than 30 centimetres (1 ft) of snowfall happen almost annually, most recently in 2022.[95][96]

Müze Gazhane in Kadıköy is the first climate change museum in Turkey.

As with virtually every part of the world, climate change is causing more heatwaves,[99] droughts,[100] storms,[101] and flooding[102][103] in Istanbul. Furthermore, as Istanbul is a large and rapidly expanding city, its urban heat island has been intensifying the effects of climate change.[104] If trends continue, sea level rise is likely to affect city infrastructure, for example Kadıkoy metro station is threatened with flooding.[105] Xeriscaping of green spaces has been suggested,[106] and Istanbul has a climate-change action plan.[107]

The Fatih district, which was named after Sultan Mehmed II (Turkish: Fatih Sultan Mehmed), corresponds to what was, until the Ottoman conquest in 1453, the whole of the city of Constantinople (today is the capital district and called the historic peninsula of Istanbul) on the southern shore of the Golden Horn, across the medieval Genoese citadel of Galata on the northern shore. The Genoese fortifications in Galata were largely demolished in the 19th century, leaving only the Galata Tower, to make way for the northward expansion of the city.[108] Galata (Karaköy) is today a quarter within the Beyoğlu (Pera) district, which forms Istanbul's commercial and entertainment center and includes İstiklal Avenue and Taksim Square.[109]

Dolmabahçe Palace, the seat of government during the late Ottoman period, is in the Beşiktaş district on the European shore of the Bosporus strait, to the north of Beyoğlu. The former village of Ortaköy is within Beşiktaş and gives its name to the Ortaköy Mosque on the Bosporus, near the Bosporus Bridge. Lining both the European and Asian shores of the Bosporus are the historic yalıs, luxurious chalet mansions built by Ottoman aristocrats and elites as summer homes.[110] Inland, north of Taksim Square is the Istanbul Central Business District, a set of corridors lined with office buildings, residential towers, shopping centers, and university campuses, and over 2,000,000 m² (22,000,000 sq ft) of class-A office space in total. Maslak, Levent, and Bomonti are important nodes within the CBD.[111][112]

The Atatürk Airport corridor is another such edge city-style business, residential and shopping corridor with over 900,000 m² (9,700,000 sq ft) of class-A office space.[112]

Originally outside the city, yalı residences along the Bosporus are now homes in some of Istanbul's elite neighborhoods.

During the Ottoman period, Üsküdar (then Scutari) and Kadıköy were outside the scope of the urban area, serving as tranquil outposts with seaside yalıs and gardens. But in the second half of the 20th century, the Asian side experienced major urban growth; the late development of this part of the city led to better infrastructure and tidier urban planning when compared with most other residential areas in the city.[113] Much of the Asian side of the Bosporus functions as a suburb of the economic and commercial centers in European Istanbul, accounting for a third of the city's population but only a quarter of its employment.[113] However, Kozyatağı–Ataşehir, Altunizade, Kavacık and Ümraniye, all together having around 1.4 million sqm of class-A office space) are now important "edge cities", i.e. corridors and nodes of business and shopping centers and of tall residential buildings.[112]

As a result of Istanbul's exponential growth in the 20th century, a significant portion of the city is composed of gecekondus (literally "built overnight"), referring to illegally constructed squatter buildings.[114] At present, some gecekondu areas are being gradually demolished and replaced by modern mass-housing compounds.[115] Moreover, large scale gentrification and urban renewal projects have been taking place,[116] such as the one in Tarlabaşı;[117] some of these projects, like the one in Sulukule, have faced criticism.[118] The Turkish government also has ambitious plans for an expansion of the city west and northwards on the European side in conjunction with the new Istanbul Airport, opened in 2019; the new parts of the city will include four different settlements with specified urban functions, housing 1.5 million people.[119]

A view of Taksim Square with the Republic Monument (1928) designed by Italian sculptor Pietro Canonica and Taksim Mosque

Istanbul does not have a primary urban park, but it has several green areas. Gülhane Park and Yıldız Park were originally included within the grounds of two of Istanbul's palaces — Topkapı Palace and Yıldız Palace—but they were repurposed as public parks in the early decades of the Turkish Republic.[120] Another park, Fethi Paşa Korusu, is on a hillside adjacent to the Bosphorus Bridge in Anatolia, opposite Yıldız Palace in Europe. Along the European side, and close to the Fatih Sultan Mehmet Bridge, is Emirgan Park, which was known as the Kyparades (Cypress Forest) during the Byzantine period. In the Ottoman period, it was first granted to Nişancı Feridun Ahmed Bey in the 16th century, before being granted by Sultan Murad IV to the Safavid Emir Gûne Han in the 17th century, hence the name Emirgan. The 47-hectare (120-acre) park was later owned by Khedive Ismail Pasha of Ottoman Egypt and Sudan in the 19th century. Emirgan Park is known for its diversity of plants and an annual tulip festival is held there since 2005.[121] The AKP government's decision to replace Taksim Gezi Park with a replica of the Ottoman era Taksim Military Barracks (which was transformed into the Taksim Stadium in 1921, before being demolished in 1940 for building Gezi Park) sparked a series of nationwide protests in 2013 covering a wide range of issues. Popular during the summer among Istanbulites is Belgrad Forest, spreading across 5,500 hectares (14,000 acres) at the northern edge of the city. The forest originally supplied water to the city and remnants of reservoirs used during Byzantine and Ottoman times survive.[122][123]

Panoramic view of Istanbul from the confluence of the Bosporus and the Sea of Marmara. Several landmarks—including Sultan Ahmed Mosque, the Hagia Sophia, Topkapı Palace, and Dolmabahçe Palace—can be seen along their shores.

Galata Tower dominates the skyline of the medieval Genoese citadel at the north of the Golden Horn.

Istanbul is primarily known for its Byzantine and Ottoman architecture. Despite its development as a Turkish city since 1453, it contains many ancient, Roman, Byzantine, Christian, Muslim, and Jewish monuments.

The Neolithic settlement in the Yenikapı quarter on the European side, which dates back to c. 6500 BCE and predates the formation of the Bosporus strait by approximately a millennium (when the Sea of Marmara was still a lake)[124] was discovered during the construction of the Marmaray railway tunnel.[26] It is the oldest known human settlement on the European side of the city.[26] The oldest known human settlement on the Asian side is the Fikirtepe Mound near Kadıköy, with relics dating to c. 5500-3500 BCE (Chalcolithic period).

There are numerous ancient monuments in the city.[125] The most ancient is the Obelisk of Thutmose III (Obelisk of Theodosius).[125] Built of red granite, 31 m (100 ft) high, it came from the Temple of Karnak in Luxor, and was erected there by Pharaoh Thutmose III (r. 1479–1425 BCE) to the south of the seventh pylon.[125] The Roman emperor Constantius II (r. 337–361 CE) had it and another obelisk transported along the River Nile to Alexandria for commemorating his ventennalia or 20 years on the throne in 357. The other obelisk was erected on the spina of the Circus Maximus in Rome in the autumn of that year, and is now known as the Lateran Obelisk. The obelisk that would become the Obelisk of Theodosius remained in Alexandria until 390 CE, when Theodosius I (r. 379–395 CE) had it transported to Constantinople and put up on the spina of the Hippodrome there.[126] When re-erected at the Hippodrome of Constantinople, the obelisk was mounted on a decorative base, with reliefs that depict Theodosius I and his courtiers.[125] The lower part of the obelisk was damaged in antiquity, probably during its transport to Alexandria in 357 CE or during its re-erection at the Hippodrome of Constantinople in 390 CE. As a result, the current height of the obelisk is only 18.54 meters, or 25.6 meters if the base is included. Between the four corners of the obelisk and the pedestal are four bronze cubes, used in its transportation and re-erection.[127]

Built by Ottoman sultans Abdülmecid and Abdülaziz, the 19th-century Dolmabahçe, Çırağan, Beylerbeyi and Küçüksu palaces on the Bosporus were designed by members of the Armenian Balyan family of court architects.[128]

Next in age is the Serpent Column, from 479 BCE.[125] It was brought from Delphi in 324 CE, during the reign of Constantine the Great, and also erected at the spina of the Hippodrome.[125] It was originally part of an ancient Greek sacrificial tripod in Delphi that was erected to commemorate the Greeks who fought and defeated the Persian Empire at the Battle of Plataea (479 BCE). The three serpent heads of the 8-meter (26 ft) high column remained intact until the end of the 17th century (one is on display at the nearby Istanbul Archaeology Museums).[129]

Built in porphyry and erected at the center of the Forum of Constantine in 330 CE to mark the founding of the new Roman capital, the Column of Constantine was originally adorned with a sculpture of the Roman emperor Constantine the Great depicted as the solar god Apollo on its top, which fell in 1106 and was later replaced by a cross during the reign of Byzantine emperor Manuel Komnenos (r. 1143–1180).[17][125]

There are traces of the Byzantine era throughout the city, from ancient churches that were built over early Christian meeting places like the Hagia Irene, the Chora Church, the Monastery of Stoudios, the Church of Sts. Sergius and Bacchus, the Church of Theotokos Pammakaristos, the Monastery of the Pantocrator, the Monastery of Christ Pantepoptes, the Hagia Theodosia, the Church of Theotokos Kyriotissa, the Monastery of Constantine Lips, the Church of Myrelaion, the Hagios Theodoros, etc.; to palaces like the Great Palace of Constantinople and its Mosaic Museum, the Palace of the Porphyrogenitus, Boukoleon Palace and Palace of Blachernae; and other public places and buildings like the Hippodrome, the Augustaion, the Basilica Cistern, Theodosius Cistern, Cistern of Philoxenos and Cistern of the Hebdomon, the Aqueduct of Valens, the Prison of Anemas, the Walls of Constantinople and the Porta Aurea (Golden Gate), among numerous others. The 4th century Harbor of Theodosius in Yenikapı, once the busiest port in Constantinople, was among the numerous archeological discoveries that took place during the excavations of the Marmaray tunnel.[26]

However, it is the Hagia Sophia that fully conveys the period of Constantinople as a city without parallel in Christendom. The Hagia Sophia, topped by a dome 31 meters (102 ft) in diameter over a square space defined by four arches, is the pinnacle of Byzantine architecture.[130] The Hagia Sophia stood as the world's largest cathedral in the world until it was converted into a mosque in the 15th century.[130] The minarets date from that period.[130] Because of its historical significance, it was reopened as a museum in 1935. However, it was re-converted into a mosque in July 2020.

Sultan Ahmed Mosque is known as the Blue Mosque due to the blue İznik tiles which adorn its interior.[131] The Obelisk of Thutmose III (Obelisk of Theodosius) is seen in the foreground.

Over the next four centuries, the Ottomans transformed Istanbul's urban landscape with a vast building scheme that included the construction of towering mosques and ornate palaces. The Sultan Ahmed Mosque (Blue Mosque), another landmark of the city, faces the Hagia Sophia at Sultanahmet Square (Hippodrome of Constantinople). The Süleymaniye Mosque, built by Suleiman the Magnificent, was designed by his chief architect Mimar Sinan, the most illustrious of all Ottoman architects, who designed many of the city's renowned mosques and other types of public buildings and monuments.[132]

Among the oldest surviving examples of Ottoman architecture in Istanbul are the Anadoluhisarı and Rumelihisarı fortresses, which assisted the Ottomans during their siege of the city.[133] Over the next four centuries, the Ottomans made an indelible impression on the skyline of Istanbul, building towering mosques and ornate palaces.

A view of Topkapı Palace, the inner core of which was built in 1459–1465, from across the Golden Horn, with the Prince Islands in the background

Topkapı Palace, dating back to 1465, is the oldest seat of government surviving in Istanbul. Mehmed II built the original palace as his main residence and the seat of government.[134] The present palace grew over the centuries as a series of additions enfolding four courtyards and blending neoclassical, rococo, and baroque architectural forms.[135] In 1639, Murad IV made some of the most lavish additions, including the Baghdad Kiosk, to commemorate his conquest of Baghdad the previous year.[136] Government meetings took place here until 1786, when the seat of government was moved to the Sublime Porte.[134] After several hundred years of royal residence, it was abandoned in 1853 in favor of the baroque Dolmabahçe Palace.[135] Topkapı Palace became public property following the abolition of monarchy in 1922.[135] After extensive renovation, it became one of Turkey's first national museums in 1924.[134]

The imperial mosques include Fatih Mosque, Bayezid Mosque, Yavuz Selim Mosque, Süleymaniye Mosque, Sultan Ahmed Mosque (the Blue Mosque), and Yeni Mosque, all of which were built at the peak of the Ottoman Empire, in the 16th and 17th centuries. In the following centuries, and especially after the Tanzimat reforms, Ottoman architecture was supplanted by European styles.[137] An example of which is the imperial Nuruosmaniye Mosque. Areas around İstiklal Avenue were filled with grand European embassies and rows of buildings in Neoclassical, Renaissance Revival and Art Nouveau styles, which went on to influence the architecture of a variety of structures in Beyoğlu—including churches, stores, and theaters—and official buildings such as Dolmabahçe Palace.[138]

Istanbul has been a cosmopolitan city throughout much of its history, but it has become more homogenized since the end of the Ottoman era. The dominant ethnic group in the city is Turkish people, which also forms the majority group in Turkey. According to survey data 78% of the voting-age Turkish citizens in Istanbul state "Turkish" as their ethnic identity.[168]

With estimates ranging from 2 to 4 million, Kurds form one of the largest ethnic minorities in Istanbul and are the biggest group after Turks among Turkish citizens.[169][170] According to a 2019 KONDA study, Kurds constituted around 17% of Istanbul's adult total population who were Turkish citizens.[168] Although the initial Kurdish presence in the city dates back to the early Ottoman period,[171] the majority of Kurds in the city originate from villages in eastern and southeastern Turkey.[172] Zazas are also present in the city and constitute around 1% of the total voting-age population.[168]

Arabs form the city's other largest ethnic minority, with an estimated population of more than 2 million.[173] Following Turkey's support for the Arab Spring, Istanbul emerged as a hub for dissidents from across the Arab world, including former presidential candidates from Egypt, Kuwaiti MPs, and former ministers from Jordan, Saudi Arabia (including Jamal Khashoggi), Syria, and Yemen.[174][175][176] As of August 2019, the number of refugees of the Syrian Civil War in Turkey residing in Istanbul was estimated to be around 1 million.[177] Native Arab population in Turkey who are Turkish citizens are found to be making up less than 1% of city's total adult population.[168] As of August 2023, there were more than 530,000 refugees of the Syrian civil war in Istanbul, the highest number in any Turkish city.[178]

Built by Suleiman the Magnificent, the Süleymaniye Mosque (1550–1557) was designed by his chief architect Mimar Sinan, the most illustrious of all Ottoman architects.[132]

2019 survey study by KONDA that examined the religiosity of the voting-age adults in Istanbul showed that 57% of the surveyed had a religion and were trying to practise its requirements. This was followed by nonobservant people with 26% who identified with a religion but generally did not practise its requirements. 11% stated they were fully devoted to their religion, meanwhile 6% were non-believers who did not believe the rules and requirements of a religion. 24% of the surveyed also identified themselves as "religious conservatives". Around 90% of Istanbul's population are Sunni Muslims and Alevism forms the second biggest religious group.[168][179]

Into the 19th century, the Christians of Istanbul tended to be either Greek Orthodox, members of the Armenian Apostolic Church or Catholic Levantines.[180] Greeks and Armenians form the largest Christian population in the city. While Istanbul's Greek population was exempted from the 1923 population exchange with Greece, changes in tax status and the 1955 anti-Greek pogrom prompted thousands to leave.[181] Following Greek migration to the city for work in the 2010s, the Greek population rose to nearly 3,000 in 2019, still greatly diminished since 1919, when it stood at 350,000.[181] There are today 50,000 to 70,000 Armenians in Istanbul[182] down from a peak of 164,000 in 1913.[183] As of 2019, an estimated 18,000 of the country's 25,000 Christian Assyrians live in Istanbul.[184]

There are 234 active churches and chapels in the city,[185] including the Church of St. Anthony of Padua on İstiklal Avenue in Beyoğlu (Pera).

The majority of the Catholic Levantines (Turkish: Levanten) in Istanbul and Izmir are the descendants of traders/colonists from the Italian maritime republics of the Mediterranean (especially Genoa and Venice) and France, who obtained special rights and privileges called the Capitulations from the Ottoman sultans in the 16th century.[186] The community had more than 15,000 members during Atatürk's presidency in the 1920s and 1930s, but today is reduced to only a few hundreds, according to Italo-Levantine writer Giovanni Scognamillo.[187] They continue to live in Istanbul (mostly in Karaköy, Beyoğlu and Nişantaşı), and Izmir (mostly in Karşıyaka, Bornova and Buca).

Istanbul became one of the world's most important Jewish centers in the 16th and 17th century.[188] Romaniote and Ashkenazi communities existed in Istanbul before the conquest of Istanbul, but it was the arrival of Sephardic Jews that ushered a period of cultural flourishing. Sephardic Jews settled in the city after their expulsion from Spain and Portugal in 1492 and 1497.[188] Sympathetic to the plight of Sephardic Jews, Bayezid II sent out the Ottoman Navy under the command of admiral Kemal Reis to Spain in 1492 in order to evacuate them safely to Ottoman lands.[188] In marked contrast to Jews in Europe, Ottoman Jews were allowed to work in any profession.[189] Ottoman Jews in Istanbul excelled in commerce and came to particularly dominate the medical profession.[189] By 1711, using the printing press, books came to be published in Spanish and Ladino, Yiddish, and Hebrew.[190] In large part due to emigration to Israel, the Jewish population in the city dropped from 100,000 in 1950[191] to 15,000 in 2021.[192][193][194]

İstiklal Avenue in Beyoğlu

Abdi İpekçi Street in Nişantaşı, Galataport Shopping Area in Karaköy and Bağdat Avenue on the Anatolian side of the city have evolved into high-end shopping districts.[240][241] Other focal points for shopping, leisure and entertainment include Nişantaşı, Ortaköy, Bebek and Kadıköy.[242] The city has numerous shopping centers, from the historic to the modern. Istanbul also has an active nightlife and historic taverns, a signature characteristic of the city for centuries, if not millennia.

The Grand Bazaar, in operation since 1461, is among the world's oldest and largest covered markets.[243][244] Mahmutpasha Bazaar is an open-air market extending between the Grand Bazaar and the Spice Bazaar, which has been Istanbul's major spice market since 1660.

Galleria Ataköy ushered in the age of modern shopping malls in Turkey when it opened in 1987.[245] Since then, malls have become major shopping centers outside the historic peninsula. Akmerkez was awarded the titles of "Europe's best" and "World's best" shopping mall by the International Council of Shopping Centers in 1995 and 1996; Istanbul Cevahir has been one of the continent's largest since opening in 2005; and Kanyon won the Cityscape Architectural Review Award in the Commercial Built category in 2006.[244] Zorlu Center and İstinye Park are among the other upscale malls in Istanbul which include the stores of the world's top fashion brands.

Süreyya Opera House is situated on the Asian side of Istanbul and Atatürk Cultural Center is the main opera house on the European side.

Along İstiklal Avenue is the Çiçek Pasajı (Flower Passage), a 19th-century shopping gallery which is today home to winehouses (known as meyhanes), pubs and restaurants.[246] İstiklal Avenue, originally known for its taverns, has shifted toward shopping, but the nearby Nevizade Street is still lined with winehouses and pubs.[247][248] Some other neighborhoods around İstiklal Avenue have been revamped to cater to Beyoğlu's nightlife, with formerly commercial streets now lined with pubs, cafes, and restaurants playing live music.[249]

Zorlu Center, designed by EAA and Tabanlıoğlu Architects, includes Zorlu PSM, the city's largest performing arts theatre and concert hall.

Istanbul is known for its historic seafood restaurants. Many of the city's most popular and upscale seafood restaurants line the shores of the Bosporus (particularly in neighborhoods like Ortaköy, Bebek, Arnavutköy, Yeniköy, Beylerbeyi and Çengelköy). Kumkapı along the Sea of Marmara has a pedestrian zone that hosts around fifty fish restaurants.[250]

The Princes' Islands, 15 kilometers (9 mi) from the city center, are also popular for their seafood restaurants. Because of their restaurants, historic summer mansions, and tranquil, car-free streets, the Prince Islands are a popular vacation destination among Istanbulites and foreign tourists.[251]

Istanbul is also famous for its sophisticated and elaborately-cooked dishes of the Ottoman cuisine. Following the influx of immigrants from southeastern and eastern Turkey, which began in the 1960s, the city's foodscape has drastically changed by the end of the century; with influences of Middle Eastern cuisine such as kebab taking an important place in the food scene.

Restaurants featuring foreign cuisines are mainly concentrated in the Beyoğlu, Beşiktaş, Şişli and Kadıköy districts.

Apart from the city's numerous stadiums, sports halls and concert halls, there are several open-air venues for concerts and festivals, such as the Cemil Topuzlu Open-Air Theatre in Harbiye, Paraf Kuruçeşme Open-Air on the Bosphorus shore in Kuruçeşme, and Parkorman in the forest of Maslak. The annual Istanbul Jazz Festival has been held every year since 1994. Organized between 2003 and 2013, Rock'n Coke was the biggest open-air rock festival in Turkey, sponsored by Coca-Cola. It was traditionally held at the Hezarfen Airfield in Istanbul.

Abdi İpekçi Street in Nişantaşı, one of Istanbul's premier shopping streets

The Istanbul International Music Festival has been held annually since 1973, and the International Istanbul Film Festival has been held annually since 1982. The Istanbul Biennial is a contemporary art exhibition that has been held biennially since 1987. The Istanbul Shopping Fest is an annual shopping festival held since 2011, and Teknofest is an annual festival of aviation, aerospace and technology, held since 2018.

When it was held for the first time in 2003, the annual Istanbul Pride became the first gay pride event in a Muslim-majority country.[252] Since 2015, all types of parades at Taksim Square and İstiklal Avenue (where, in 2013, the Gezi Park protests took place) have been denied permission by the AKP government, citing security concerns, but hundreds of people have defied the ban each year. Critics have claimed that the bans were in fact due to ideological reasons.

Istanbul's motorways network are the O-1, O-2, O-3, O-4 and O-7. The total length of Istanbul Province's toll motorways network (otoyollar) is 543 km (337 mi) (2021) and the state highways network (devlet yollari) is 353 km (219 mi) (2021), totaling 896 km (557 mi) of expressway roads (minimum 2x2 lanes), excluding secondary roads and urban streets.[312][313][314] The density of expressway network is 16.8 km/100 km². The O-1 forms the city's inner ring road, traversing the 15 July Martyrs (First Bosphorus) Bridge, and the O-2 is the city's outer ring road, crossing the Fatih Sultan Mehmet (Second Bosphorus) Bridge. The O-2 continues west to Edirne and the O-4 continues east to Ankara. The O-2, O-3, and O-4 are part of European route E80 (the Trans-European Motorway) between Portugal and the Iran–Turkey border.[315] In 2011, the first and second bridges on the Bosphorus carried 400,000 vehicles each day.[316] The O-7[317] or Kuzey Marmara Otoyolu, is a motorway that bypass Istanbul to the north. The O-7 motorway from Kinali Gişeleri to Istanbul Park Service has 139.2 km (86.5 mi), with 8 lanes (4x4), and from Odayeri-K10 to Istanbul Atatürk Airport has 30.4 km (18.9 mi).[314] The completed section of highway crosses the Bosphorus Strait via the Yavuz Sultan Selim (Third Bosphorus) Bridge, entered service on 26 August 2016.[318] The O-7 motorway connects Istanbul Atatürk Airport with Istanbul Airport. Environmentalist groups worry that the third bridge will endanger the remaining green areas to the north of Istanbul.[319][320] Apart from the three Bosphorus Bridges, the dual-deck, 14.6-kilometer (9.1 mi) Eurasia Tunnel (which entered service on 20 December 2016) under the Bosphorus strait also provides road crossings for motor vehicles between the Asian and European sides of Turkey.[321] Road transport emits significant carbon dioxide, estimated at 7 million tons in 2021.[322]

Istanbul's nostalgic and modern tram systems

Istanbul's local public transportation system is a network of commuter trains, trams, funiculars, metro lines, buses, bus rapid transit, and ferries. Fares across modes are integrated, using the contactless Istanbulkart, introduced in 2009, or the older Akbil electronic ticket device.[323] Trams in Istanbul date back to 1872, when they were horse-drawn, but even the first electrified trams were decommissioned in the 1960s.[324] Operated by Istanbul Electricity, Tramway and Tunnels General Management (İETT), trams slowly returned to the city in the 1990s with the introduction of a nostalgic route and a faster modern tram line, which now carries 265,000 passengers each day.[324][325] The Tünel opened in 1875 as the world's second-oldest subterranean rail line (after London's Metropolitan Railway).[324] It still carries passengers between Karaköy and İstiklal Avenue along a steep 573-meter (1,880 ft) track; a more modern funicular between Taksim Square and Kabataş began running in 2006.[326][327]

Boğaziçi University station of the Istanbul Metro

Marmaray commuter rail at Ayrılıkçeşmesi station

The Istanbul Metro comprises ten lines (the M1, M2, M3, M6, M7, M9 and M11 on the European side, and the M4, M5 and M8 on the Asian side) with several other lines (M12 and M14) and extensions under construction.[328][329] The two sides of Istanbul's metro are connected under the Bosphorus by the Marmaray Tunnel, inaugurated in 2013 as the first rail connection between Thrace and Anatolia, having 13.5 km (8.4 mi) length.[330] The Marmaray tunnel together with the suburban railways lines along the Sea of Marmara, form the intercontinental commuter rail line in Istanbul, named officially B1, from Halkalı on the European side to Gebze on the Asian side. This rail line has 76.6 km (47.6 mi), and the full line opened on 12 March 2019.[331] Until then, buses provide transportation within and between the two-halves of the city, accommodating 2.2 million passenger trips each day.[332] The Metrobus, a form of bus rapid transit, crosses the Bosphorus Bridge, with dedicated lanes leading to its termini.[333]

İDO (Istanbul Seabuses) runs a combination of all-passenger ferries and car-and-passenger ferries to ports on both sides of the Bosphorus, as far north as the Black Sea.[334][335] With additional destinations around the Sea of Marmara, İDO runs the largest municipal ferry operation in the world.[336] The city's main cruise ship terminal is the Port of Istanbul in Karaköy, with a capacity of 10,000 passengers per hour.[337] Most visitors enter Istanbul by air, but about half a million foreign tourists enter the city by sea each year.[338]

Originally opened in 1873 with a smaller terminal building as the main terminus of the Rumelia (Balkan) Railway of the Ottoman Empire, which connected Istanbul with Vienna, the current Sirkeci Terminal building was constructed between 1888 and 1890, and became the eastern terminus of the Orient Express from Paris.[339]

International rail service from Istanbul launched in 1889, with a line between Bucharest and Istanbul's Sirkeci Terminal, which ultimately became famous as the eastern terminus of the Orient Express from Paris.[76] Regular service to Bucharest and Thessaloniki continued until the early 2010s, when the former was interrupted for Marmaray construction but started running again in 2019 and the latter was halted due to economic problems in Greece.[340][341] After Istanbul's Haydarpaşa Terminal opened in 1908, it served as the western terminus of the Baghdad Railway and an extension of the Hejaz Railway; today, neither service is offered directly from Istanbul.[342][343][344] Service to Ankara and other points across Turkey is normally offered by Turkish State Railways, but the construction of Marmaray and the Ankara-Istanbul high-speed line forced the station to close in 2012.[345] New stations to replace both the Haydarpaşa and Sirkeci terminals, and connect the city's disjointed railway networks, now the Marmaray second phase opened to the public.[345] Private bus companies still operation to this day. Istanbul's main bus station is the largest in Europe, with a daily capacity of 15,000 buses and 600,000 passengers, serving destinations as distant as Frankfurt.[346][347]

Istanbul had three large international airports, two of which currently serve commercial passenger flights. The largest is the new Istanbul Airport, opened in 2018 in the Arnavutköy district to the northwest of the city center, on the European side, near the Black Sea coast.

Istanbul Airport

Sabiha Gökçen Airport

All scheduled commercial passenger flights were transferred from Istanbul Atatürk Airport to Istanbul Airport on 6 April 2019, following the closure of Istanbul Atatürk Airport for scheduled passenger flights.[348] The IATA airport code IST was also transferred to the new airport.[349] Once all phases are completed in 2025, the airport will have six sets of runways (eight in total), 16 taxiways, and will be able to accommodate 200 million passengers a year.[350][351] The transfer from the airport to the city is via the O-7, and it will eventually be linked by two lines of the Istanbul Metro.

Sabiha Gökçen International, 45 kilometers (28 mi) southeast of the city center, on the Asian side, was opened in 2001 to relieve Atatürk. Dominated by low-cost carriers, Istanbul's second airport has rapidly become popular, especially since the opening of a new international terminal in 2009;[352] the airport handled 14.7 million passengers in 2012, a year after Airports Council International named it the world's fastest-growing airport.[353][354] Atatürk had also experienced rapid growth, as its 20.6 percent rise in passenger traffic between 2011 and 2012 was the highest among the world's top 30 airports.[355]

Istanbul Atatürk Airport, located 24 kilometers (15 mi) west of the city center, on the European side, near the Marmara Sea coast, was formerly the city's largest airport. After its closure to commercial flights in 2019, it was briefly used by cargo aircraft and the official state aircraft owned by the Turkish government, until the demolition of its runway began in 2020. It handled 61.3 million passengers in 2015, which made it the third-busiest airport in Europe and the 18th-busiest in the world in that year.[355]

Atatürk Arboretum is an arboretum and city forest located in Bahçeköy, Sarıyer.

The natural vegetation cover of the Bosporus region is made up of temperate broadleaf and mixed forests and pseudo-maquis. Chestnut, oak, elm, linden, ash and locust comprises the most prominent tree genera. The most important species belonging to maquis formation are laurel, terebinth, Cercis siliquastrum, broom, red firethorn, and oak species such as Quercus cerris and Quercus coccifera. Apart from the natural flora Platanus orentalis, horse chestnut, cypress and stone pine make up the introduced species that got acclimatized to Istanbul.[356] In a study that examined urban flora in Kartal, a total of 576 plant taxa were recorded; of those 477 were natural and 99 were exotic and cultivated. The most native taxa were in the Asteraceae family (50 species), while the most diverse exotic plant family was Rosaceae (16 species).[357]

Turkish Straits and Sea of Marmara play a vital role for migrating fish and other marine animals between Mediterranean, Marmara and Black Sea. Bosporus hosts pelagic, demersal and semipelagic fish species and more than 130 different taxa have been documented in the strait.[358] Bluefish, bonito, sea bass, horse mackerel and anchovies composes the economically important species. Fish diversity in the waters of Istanbul has dwindled in the recent decades. From around 60 different fish species recorded in the 1970s only 20 of them still survive in the Bosporus.[359]Common bottlenose dolphin (Turkish: afalina), short-beaked common dolphin (Turkish: tırtak) and harbor porpoise (Turkish: mutur) make up the marine mammals presently found in the Bosporus and surrounding waters, though since the 1950s the number of dolphin observations has become increasingly rare. Mediterranean monk seals were present in Bosporus, and Princes' Islands and Tuzla shores were seal breeding areas during summer, but they have not been observed in Istanbul since the 1960s and thought to be extinct in the region.[360] Water pollution, overfishing and destruction of coastal habitats caused by urbanization are main threats to Istanbul's marine ecology.

Street cats in the city

Wild land mammals are mainly concentrated in the northern forested areas of Istanbul. Roe deer, wild boars, foxes, coyotes, martens, badgers, wolves, weasels, wildcats, squirrels and reed cats have been documented to live inside the boundaries of Istanbul Province.[361] Apart from the wild land mammals Istanbul hosts a sizeable stray animal population. The presence of feral cats in Istanbul (Turkish: sokak kedisi) is noted to be very prevalent, with estimates ranging from a hundred thousand to over a million stray cats. The feral cats in the city have gained widespread media and public attention and are considered to be symbols of the city.[362][363] Rose-ringed parakeet colonies are present in urban areas, similar to other European cities as feral parrots, and considered as invasive species.[364]

Air pollution in Turkey is acute in İstanbul with cars, buses and taxis causing frequent urban smog,[365] as it is one of the few European cities without a low-emission zone. As of 2019 the city's mean air quality remains of a level so as to affect the heart and lungs of healthy street bystanders during peak traffic hours,[366] and almost 200 days of pollution were measured by the air pollution sensors at Sultangazi, Mecidiyeköy, Alibeyköy and Kağıthane.[367] It is one of the 10 worst cities for NO₂.[368]

Algal blooms and red tides were reported in Sea of Marmara and Bosporus (especially in Golden Horn), and regularly happen in urban lakes such as Lake Büyükçekmece and Küçükçekmece. In June 2021, a marine mucilage wave allegedly caused by water pollution spread to Sea of Marmara.[369]