Little remains of the 5th-century church that was originally built here atop a well sacred to Juno. But that shouldn’t detract from what is a very pretty basilica, complete with a Romanesque bell tower and a 12th-century columned portico. Inside, the otherwise standard baroque decor is elevated by Guido Reni’s Crocifisso (Crucifixion) over the main altar, and a fine bust by Bernini in the Cappella dell'Annunziata.
The French painter Nicholas Poussin, who died in 1655, is buried in the church.