The nave is articulated by arcades on antique grey marble columns, probably coming from Roman constructions.

A church and an abbey in Perugia. The Benedictine monastery was created around 996 over the former cathedral church. Its early patron was Pietro Vincioli (died 1007), a Perugian noble, later canonized. Pope Eugenius IV ordered the transfer of the abbey to the Cassinese Congregation, a reformed Benedictine congregation in 1436. From this point, it had an prior rather than an abbot. The church has a monumental facade with three arcades, designed around 1614 by the Perugine architect Valentino Martelli: the first cloister is also by Martelli, with the second floor completed by Lorenzo Petrozzi. The polygonal belltower, on the right of the portal, was rebuilt in 1463-1468 with Florentine-Gothic lines, based on a design by Bernardo Rossellino.