In the sacristy and the corridor leading to it are several fresco fragments. Most of these were transferred here after from the 7th century oratory after it was excavated, and are of the highest interest. There are fragments from two separate decoratives schemes, one 7th century and the other, 10th century.
The crypt now comprises the original semi-circular crypt under the sanctuary, and the void dug out under the nave by the archaeologists in order to uncover the remains of the original 7th century monastic oratory. By tradition, this was originally the house of St Silvia, it was actually a late 4th century aula belonging to a large private house.
