The Good Shepherd and other scenes from the Catacomb of
Saints Peter and Marcellinus, Rome, 4th century.
Christ among his disciples (the Last Supper?) from the
Catacomb of Domatilla, Rome, 4th century.
THE BASILICAN PLAN CHURCH
Constantine was the first great patron of monumental Christian architecture. Shortly after he issued the
Edict of Milan, which allowed Christians to worship freely, the enormous church of St. Peter’s was begun.
This church, called Old St. Peter’s because it was replaced in the sixteenth century, used the plan of the
Roman basilica for its basic form, but the basilica plan was modified in several ways to conform to the new
liturgical needs of the church. The basic configuration of nave and aisles was kept, but the entrance was
moved to one of the building’s short ends, thus creating a processional path to the altar, which was placed
at the opposite end of the entrance. The apse, also found in Roman basilicas, gave emphasis to the altar
area. A transept crossed the nave and aisles near the apse, while the altar itself was set over the tomb of
St. Peter, the saint Jesus appointed to be his successor.
Old St. Peter’s, reconstruction of appearance, c. 330. Plan of Old St. Peter’s
Two other elements in the Christian basilica were derived from the Roman building type. In front of the
church, the atrium is an open courtyard; unlike the Roman atrium, however, the church atrium is as wide
as the church and is connected to the church by the narthex—a porch or entrance hall. The Christian
basilica also uses the triumphal arch, but what was a freestanding gateway in Roman architecture is
transformed into an arch on the church’s interior that frames the area around the altar.