Bramante and Sangallo
1506-1515
Bramante, the original architect of the St. Peter's Basilica, was inspired by the Pantheon. The dome would follow a similar profile, except for the lantern. The supporting wall would become a drum raised on four piers. The wall would be lightened with the help of windows and a peristyle.
Sangallo, who took over in 1513, found inspiration from the Florence Cathedral as well as the Pantheon. He developed on Bramante's plan and converted the peristyle into a series of arched and ordered openings around the base, with a second such arcade in a tier above the first. The lantern became a massive structure, surrounded by a projecting base, and peristyle. This would have been surmounted by a conical spire.