Bramante's dome was to be like the one on the Pantheon. But there was one very big difference between the Pantheon dome and Bramante's design. The Pantheon's dome stands on a round wall like a drum, with only one doorway in it, but Bramante's dome was designed to stand on a drum, which was standing high up on four wide arches. The aches rested on four enormous "piers" (pillars of stone). He had got this idea from Florence Cathedral which had an enormous dome resting on eight big piers. Another idea that Bramante got from Florence Cathedral was the design for the little stone tower which sits on top of the dome and is called the "lantern".