The oldest and most important Christian site on the Roman Forum, this ancient church is a unique treasure trove of early Christian art. Its cavernous interior, reopened in 2016 after a lengthy restoration, is lined with exquisite 6th- to 9th-century frescoes. Particularly impressive is an image on the east wall showing Christ with the founding fathers of the Eastern and Western churches, and a hanging depiction of the Virgin Mary with child, one of the oldest icons in existence.
The church, which was originally built inside a complex of Roman buildings, was buried in rubble during an earthquake in 847 and only rediscovered in 1900.
Entry is with the SUPER ticket, which also covers the nearby Oratorio dei Quaranta Martiri and Rampa di Domiziano.