Old St. Peter's Basilica - Design

Design

The design was a typical basilica form with the plan and elevation resembling those of Roman basilicas and audience halls, such as the Basilica Ulpia in Trajan's Forum and Constantine's own Aula Palatina at Trier, rather than the design of any Greco-Roman temple.

Constantine went to great pains to build the basilica on the site of St. Peter's grave, and this fact influenced the layout of the building. The Vatican Hill, on the west bank of the Tiber River, was leveled. Notably, since the site was outside the boundaries of the ancient city, the apse with the altar was located in the west so that the basilica's façade could be approached from Rome itself to the east. Since the custom was to offer Mass ad orientem, (i.e. facing eastward), this meant that popes offering Mass in the basilica unintentionally faced the congregation.

The church was capable of housing from 3,000 to 4,000 worshipers at one time. It consisted of five aisles, a wide central nave and two smaller aisles to each side, which were each divided by 21 marble columns, taken from earlier pagan buildings. It was over 350 feet (110 m) long, built in the shape of a Latin cross, and had a gabled roof which was timbered on the interior and which stood at over 100 feet (30 m) at the center. An atrium, known as the Garden of Paradise, stood at the entrance and had five doors which led to the body of the church, but was actually a sixth century addition.

The great Navicella mosaic (1305-1313) in the atrium is attributed to Giotto di Bondone. The giant mosaic, commissioned by Cardinal Jacopo Stefaneschi, occupied the whole wall above the entrance arcade facing the courtyard. It depicted St. Peter walking on the waters. This extraordinary work was mainly destroyed during the construction of the new St. Peter's in the 16th century, but fragments were preserved. Navicella means "little ship" referring to the large boat which dominated the scene, and whose sail, filled by the storm, loomed over the horizon. Such a natural representation of a seascape was known only from ancient works of art.

The nave ended with an arch, which held a mosaic of Constantine and Saint Peter, who presented a model of the church to Christ. On the walls, each having 11 windows, were frescoes of various people and scenes from both the Old and New Testament.

The fragment of an eighth-century mosaic, the Epiphany is one of the very rare remaining bits of the medieval decoration of Old St. Peter's Basilica. The precious fragment is kept in the sacristy of Santa Maria in Cosmedin. It proves the high artistic quality of the destroyed mosaics. Another one, a standing madonna is on a side altar in the Basilica of San Marco in Florence.

The exterior however, unlike earlier pagan temples, was not lavishly decorated.

The altar of the Old St. Peter's used several Solomonic columns. According to tradition, Constantine took these columns from the Temple of Solomon and gave them to the church; however, the columns were probably from an Eastern church. When Gian Lorenzo Bernini built his baldacchino to cover the new St. Peter's altar, he drew from the twisted design of the old columns. Eight of the original columns were moved to the piers of the new St. Peter's.