Let us move near the second column of the left nave. On the floor, close to the base, at the end of the cross that decorates the pavement of the central nave, one can admire the funerary inscription of Severus, dating to the 5th century AD. The inscription lacks the left-hand portion and the upper lines. The renowned scholar Onofrio Panvinio (1529–1568) copied and transcribed an inscription identical to this one from Argentella, though four lines longer and likewise missing the left side. He listed it among Roman inscriptions, without specifying the place where he had the opportunity to see it. On the basis of his testimony, some scholars believe that it was transferred from Rome to Argentella during the 18th century. However, at that time the abbey had already been abandoned for three centuries, which is why other scholars instead maintain that Panvinio read and copied it right here in Palombara.
Let us now return toward the center of the main nave. In front of the steps leading to the presbytery, one can notice in the pavement a different arrangement of some bricks compared to the others: these bear witness to the presence, beneath the current floor, of three sections of wall belonging to the original oratory dating from the 6th to the 8th century, discovered during the 1970s in the course of floor restoration works. The first place of worship was considerably smaller than the present 12th-century church and was enlarged for the first time during the 9th century.
We now descend into the crypt, using the staircase located at the end of the left nave.
