After his victory in 312 constantine initiated construction of a series of churches and shrines at Rome. The most impressive was an enormous monumental complex on the Vatican Hill. The approach to this complex eventually included an expansive courtyard and a porch leading to a large church dedicated to St. Peter. Within the church a transept divided the long central nave and its side aisles from the apse. In front of the apse, at the center of the transept, was a shrine commemorating the tomb of St. Peter. This church quickly became a favorite recipient of imperial patronage. Later traditions claimed that Constantine endowed it with extensive properties, and that he and his mother, Helena, presented the shrine with a large cross of gold.

Although primarily a remembrance of St. Peter, this church also commemorated Constantine. On the arch that separated the nave from the transept an inscription recalled his success and generosity. “Under your leadership the world has raised itself triumphant to the stars. As a result, Constantine the victor has built this hall for you.” With a dedication that attributed the emperor's military victories to God's guidance this arch became the equivalent of a Christian response to the Arch of Constantine that stood in the symbolic heart of the city. On that triumphal arch the senate and people of Rome had interpreted the emperor's victory in a “Republican” context as the liberation of the capital.