The basilica acted as bishop's seat until 1007. Six years later bishop Alberic moved the seat within the walls. The basilica was then entrusted to the Benedictines who, between 1050 and 1095, rebuilt it in Romanesque style. The new edifice was dedicated to Amantius' successor, Abundius. The structures of the Palaeo-Christian church, discovered in 1863 during a restoration, are still marked by black and pale marble stones in the pavement.
