San Basilio al Foro di Augusto, Demolished church site in Monti, Rome, Italy

San Basilio al Foro di Augusto was a Catholic church and adjoining monastery in the Monti district, built against the high enclosure wall of the Forum of Augustus on the podium of the Temple of Mars Ultor. Under Pius V the Dominican nuns rebuilt it, opening windows and a portal in the forum wall toward Via Tor de' Conti. Its interior had frescoes by Marco Tullio Montagna and an altarpiece of the Annunciation, a copy by Gaetano Lapis after Guido Reni.

First mentioned in a bull of Pope Agapito II in 955 as San Basilio in scala mortuorum, named for the stairway leading to an underground cemetery, the church and its monastery stood on the podium of the Temple of Mars Ultor. In the 16th century Pius V gave the complex to Dominican nuns, who rebuilt it and renamed it Santissima Annunziata. Its 13th-century bell tower was demolished in 1838, and church and monastery were destroyed in 1924 during the archaeological excavations of the forum.

The name San Basilio in scala mortuorum referred to the small stair that led down to an underground cemetery beside the church. Under Pius V the complex passed to Dominican nuns, who rebuilt it and renamed it Santissima Annunziata ai Pantani, after the nearby Arco dei Pantani. Inside, Marco Tullio Montagna painted the walls, while the main altar held Gaetano Lapis's copy of Guido Reni's Annunciation.

The former site of the church can be identified on Via Tor de' Conti through visible architectural fragments from the original entrance. This location sits within an archaeological zone where visitors can observe both Roman and medieval layers of the city's past.

The only surviving element is the church's original entrance portal, walled up but left in its original position on the outer face of the Forum of Augustus enclosure wall on Via Tor de' Conti. The 13th-century bell tower, which stood above the surviving columns of the Temple of Mars Ultor, was demolished in 1838 during restoration work around the forum.