Sanctuary of Santa Maria dell'Acquasanta

The facade and narthex of the sanctuary were made in 1819 by architect Matteo Lovatti,[17][18][19] also active in the same period in Velletri and Albano Laziale and awarded for his artistic merits the Order of St. Sylvester Pope,[17] with funding from the canon regular of the basilica of St. Barnabas Francesco Fumasoni Biondi.[17][19]

The facade elevation, neoclassical in style,[19] is made entirely of peperino, with an entrance "in antis" (i.e., punctuated by two Tuscan columns)[19] holding a molded architrave supported by a corbel that runs along the entire facade elevation.[17][24] The wrought-iron gate that closes the narthex outside was placed in 1865, and is now replaced with a stained glass window.[19] On the entablature of the facade the following inscription reads:

The interior of the narthex is bare, raised three steps above street level (a difference in height reduced to one step after the sanctuary square was paved in sanpietrini in the early 20th century).[19] The inner doorway of the church, originally located directly outside, was made in the 18th century and features molded imposts[24] and an arched tympanum in the center of which a coat of arms was probably placed, as depicted by some prints and drawings.[22]

The interior of the sanctuary has a single nave, with the right side carved entirely out of peperino, so that the only window is located on the left wall, above the altar of the Most Holy Crucifix, the church's only side altar. The presence of ogives would suggest that originally the walls and vault were plastered,[9] however in its present state the rock is left exposed, with patches of moisture evident in places. The perimeter of the hall is traversed by a sturdy cornice.[9]

In the right wall there is a cut in the peperino, probably an ancient aqueduct that served the cave near the sanctuary, which some have speculated to be a Roman or pre-Roman sanctuary, located near the Ferentano Woods consecrated to the indigenous Latin deity Ferentina.

On the left wall, there is a marble plaque affixed by Calabrian priests Giovanni Andrea and Nicola Fico in 1788 in celebration of their funding for the construction of the side altar of the Holy Crucifix.[16] The plaque reads as follows:

Another view of the sanctuary. Note the bell placed on the roof of the sacristy, to the left of the church, after the small bell tower was demolished.

The same altar of the Crucifix was thus built at the end of the eighteenth century out of devotion to these two Calabrian priests, and it does not present any notable details of attention, also because it was remodeled at various times: the Secular Franciscan Order, for example, had its own coat of arms in white marble on a blue field affixed in the oval of the tympanum.[16] Between 1823 and 1824 the same canon Fumasoni Biondi who had financed the construction of the facade donated a life-size wooden crucifix to the altar and asked Massimo d'Azeglio, who was vacationing in Marino at the time, to make a pictorial frame for the sacred image.[20] Moreover, the painter, a future president of the Council of Ministers of the Kingdom of Italy, was helped in the work by two brigands who had taken refuge in the sanctuary to escape arrest,[20] a sign that it was possible for common criminals to have the right of asylum in the sanctuary. Currently, both the crucifix, which was probably moved before World War II to the basilica of St. Barnabas and replaced with a 19th-century polychrome wooden crucifix of medium size,[21] and the fresco have been lost. Marinese historian Girolamo Torquati believes that the Most Holy Crucifix of Marino was originally displayed in the sanctuary, an image that began to work miracles in June 1635,[26] and was moved to the church of the Holy Trinity, where it is still kept, by the religious congregation of the Clerics Regular Minor in June 1637.[27]

The high altar, carved from a large block of isolated peperino stone probably in the eighteenth century,[16][24] houses the Marian image framed by festoons and stucco volutes,[16] and surmounted by two broken tympanums in the center of which reads the inscription in Latin: "apud Te est fons vitae - Psal XXXV" ("at you is the source of life," "Psalm 35").[16] On the two tympanums, two small statues depicting curly-haired children are placed:[24] in the center, a small roundel depicting God and the Holy Spirit stands to represent, in connection with the Child Jesus below, the Trinity.[16]

Access to the sacristy is provided by a bronze door, a recent work by Marinese painter and sculptor Stefano Piali (2005[28]), depicting the miracle of Our Lady of Aquasanta. The peperino imposts of the door are ancient.[9]

The sacristy room is a rectangular room with a pavilion-vaulted ceiling covered with eighteenth-century stuccoes now largely ruined.[9] Outside the sacristy is a small garden, which scholar Vincenzo Antonelli speculates was the "kitchen garden" that gave the place of worship its first name:[9] Here is located the staircase carved into the peperino stone that was the original access to the Marian image before the church was built.

The rectory tower and, at lower right, the cut in the rock cliff.

Above the church rises a two-story tower, which already existed in the second half of the 16th century and was raised in the late 18th century. At the top of the tower stood a small bell gable, demolished in the 1920s: of the two bells placed there, one has been lost, while the other is still used inside the sanctuary. Both were cast on the same date the bell tower was built, 1792, thanks to funding from the aforementioned Calabrian priests Giovanni Andrea and Nicola Fico.[16]

An epigraph celebrating the work done in the church on this occasion is placed on the wall of the tower facing Antonio Fratti Street: