San Petronio, Bologna

The Porta Magna with sculpture by Jacopo della Quercia

In 1388, the Consiglio Generale dei Seicento prepared the construction of the church as a civic temple.[1] To make room for the church, the adjacent Curia of Sancti Ambrosii was demolished, together with the majority of one of the city's burgs, including at least eight churches and towers. The first stone of construction was laid on 7 June 1390 under the supervision of architect Antonio di Vincenzo.[1] Works lasted for several centuries: after the completion of the first version of the facade, in 1393 the first pair of side chapels were begun. The series were completed only in 1479.

The third bay was built in 1441–1446. Its construction was delayed by the cardinal Baldassarre Cossa, who sold the construction material of the basilica and kept the money.[2]

San Petronio Basilica and Piazza Maggiore.

In 1514, Arduino degli Arriguzzi was chosen as the architect to construct the dome. His proposal included a large dome resting upon the width between the side aisles, which necessitated larger transepts and apses.[2][3] The project was considered too complicated, and after building the first two pillars and two triangular pylons for the dome, the work was halted.[2] According to legend, Pope Pius IV halted the "megalomaniac dream" and instead encouraged the construction of the Archiginnasio of Bologna.[3]

The basilica is a large church measuring 132 metres long, 66 metres wide, and 47 metres tall, and is described as the "most imposing" church in Bologna.[3] The façade was designed by Domenico da Varignana and started in 1538 by Giacomo Ranuzzi. However, it remains unfinished.[3]

The main doorway (Porta Magna) was decorated by Jacopo della Quercia of Siena with scenes from the Old Testament on the pillars, eighteen prophets on the archivolt, scenes from the New Testament on the architrave, and a Madonna and Child, Saint Ambrose and Saint Petronius on the tympanum. It is flanked by two side doors, with Alfonso Lombardi's Resurrection on the left and Amico Aspertini's Deposition on the right.[3]

The central nave covering and apse shooting were completed in 1663, designed by Girolamo Rainaldi and directed by Francesco Martini. The lower naves are enclosed by rectilinear walls. The first two windows were designed by Antonio with the assistance of Francesco di Simone, Domenico da Milano, Pagno di Lapo Portigiani and Antonio di Simone. The bell tower was designed by Giovanni da Brensa and built between 1481 and 1487.[3] In 2017, the proposal for completing the facade by Inter-Esse Studio was awarded the first place in the international competition of wall was held by CODE – Competitions for Designers and Con-fine Art.[4]

• Details of the decoration of the main doorway by Jacopo della Quercia, photographed by Paolo Monti
• 
  Original sin
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  Fall of man
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  Noah's Ark
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  Binding of Isaac
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  Prophets on the archivolt
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  Massacre of the Innocents

The nave, with Vignola's ciborium

The interior houses a Madonna with Saints by Lorenzo Costa the Younger, and a Pietà by Amico Aspertini.

The altar contains a 15th-century wooden crucifix. At the back, a fresco of the Madonna with St. Petronio by Marcantonio Franceschini and Luigi Quaini, cartoons by Cignani (1672). The ciborium of the main altar was built in 1547 by Jacopo Barozzi da Vignola.[3]

The fifteenth-century wooden choir was completed by Agostino de 'Marchi. The vaulting and decoration of the central nave is by Girolamo Rainaldi, who completed them in 1646–1658.

The nave contains twenty-two side chapels:

1. Chapel of St. Abbondio, formerly of the Dieci di Balia – restored in neo-Gothic style in 1865. In this chapel, in the year 1530, Emperor Charles V was crowned by Pope Clement VII.
2. Chapel of St. Petronio, once of the Cospi and Aldrovandi families, designed by Alfonso Torreggiani, designed to contain the relic of the head of San Petronio.
3. Chapel of St. Ivo, Formerly of the family of San Brigida dei Foscherari: it has statues of Angelo Piò and the paintings of the Madonna of St. Luke and Saints Emidio and Ivo by Gaetano Gandolfi and Apparition of the Virgin to St. Francesca Romana by Alessandro Tiarini (1615). On the pillar, two clocks, one of the first made in Italy with the correction of the pendulum (1758).
4. Chapel of the Magi, once of Bolognini family: its marble Gothic balustrade designed by Antonio di Vincenzo (1400); the Triptych wooden altar with twenty-seven figures carved and painted by Jacopo di Paolo. The walls were painted by Giovanni di Pietro Falloppi/Giovanni da Modena with a cycle depicting the Episodes in the life of San Petronio, the back wall, right wall, Stories of the Three Kings; the left wall, at the top, The Last Judgment with the Coronation of the Virgin in oval, and the controversial Heaven and Hell, Dante's depiction of the places, with a gigantic figure of Lucifer.
5. Chapel of St. Sebastian, once of Vaselli family.
6. Chapel of St. Vincent Ferrer, formerly of the Griffoni, and Cospi-Ranuzzi families: bronze monument of Cardinal Giacomo Lercaro made by Giacomo Manzù (1954).
7. Chapel of St. James, formerly of the Rossi and Baciocchi families: the Madonna Enthroned on the altar was painted by Lorenzo Costa (1492), to the same author attributed the designs of the stained glass. Funeral monument containing the remains of Prince Felix Baciocchi and his wife Elisa Bonaparte (1845).
8. Chapel of St. Rocco, formerly of the Ranuzzi family: it contains a Saint Roch with a Donor by Parmigianino (1527).
9. Chapel of St. Michael formerly of the Barbazzi and Manzoli families: it houses a painting of Archangel Michael defeating the Fallen Angels by Denys Calvaert (1582).
10. Chapel of St. Rosalie, formerly of the Sixteen of the Senate, now the Town Hall: canvas of Glory of Santa Barbara by Tiarini.
11. Chapel of St. Bernardino stands before the fifteenth-century organ case by Lorenzo da Prato, the chapel was painted in 1531 by Aspertini with Four Stories of St. Petronius.
12. Chapel of the Relics, formerly of Zambeccari family.
13. Chapel of St. Peter Martyr, formerly the Society of Beccari, with marble railing by Francesco di Simone (late fifteenth century);
14. Chapel of St. Anthony of Padua, formerly of Saraceni and Cospi families: the statue of St. Anthony of Padua attributed to Jacopo Sansovino.
15. Chapel of the Blessed Sacrament, formerly of the Malvezzi Campeggi, rebuilt in the nineteenth.
16. Chapel of the Immaculate, formerly of Fantuzzi family: art nouveau decorations by Achille Casanova.
17. Chapel of St. Jerome, formerly of the Castelli: the St. Jerome altar attributed to Lorenzo Costa.
18. Chapel of St. Lorenzo, formerly of the Garganelli, Ratta and Pallotti families: the Pieta was painted by Aspertini.
19. Chapel of the Cross, formerly of the Notai: with devotional frescoes depicting Saints by Francesco Lola, Giovanni Pietro Falloppi and Pietro Lianori (XV). The window was made by Blessed Fra Giacomo di Ulm designed by Michele di Matteo da Bologna.
20. Chapel of St. Ambrose, formerly of the Marsili, with a fresco in the style of Vivarini (mid-15th century).
21. Chapel of St. Bridget, formerly of the Pepoli: polyptych by Tomas Garelli (1477).
22. Chapel of Our Lady of Peace: Madonna in Istrian stone by Giovanni Ferabech (1394).