This space was originally uncovered: it was a kind of portico, which was later vaulted by the Guglielmite monks during the 13th century. In fact, when facing the church it is possible to make out the lower part of what was originally the façade of the Romanesque church. Two windows and the portal can be seen, with doorjambs that still preserve the slots of the closing system for the wooden door, just as the windows of the vestibule are still visible on the opposite wall. The entire façade of the church was frescoed during the 12th century.
In this area there is also a sarcophagus, later than the previous one, dating to the 5th century AD.
