The church of S.Giovanni was originally called Santa Reparata as can be seen in a document dated 754 A.D. Later, in the year 881A.D., it was dedicated to St. John the Baptist, while in 984 A.D., Santa Reparata and San Giovanni were worshipped. However, owing to archaeological discoveries, the foundations of the church itself are much older, dating back to Roman times. In 1692, a marble sarcophagus was discovered belonging to the Augustan age. It is now kept in the Archbishop’s palace. In 1714, a marble urn was discovered, deep-set under the altar which contained a glass vase and the body of S. Pantaleone. In 1885, Ridolfi discovered four different layers or foundations below the church. The deepest layer, many feet below the level of the existing church contains part of a Roman mosaic pavement belonging to the 1st Century of the Empire. This black and white mosaic discovered by Ridolfi is now safeguarded in the 1st hall of the National Museum of Villa Guinigi.