 Perhaps in this period, when Roman imperial authority in Italy had diminished, the mausoleum to the south of the basilica was transformed into a chapel dedicated to St Genesius the martyr.By the sixth century, on the east wall, opposite the entrance, two portals were opened giving access to two local apses.In the tenth century, probably in the Ottonian era, reconstruction took place possibly involving the participation of a Byzantine workforce who had retained knowledge of the classical techniques of construction and decoration.