The engineering of the roof of the Pantheon. 360. Key is sequence of the buttresses seen in profile and from air. Even more info than ribbing, this is a buttress turned 360. Dome =arch swung 360
Completed AD 123/Dia Dome 142 ft, Hag Soph 102 ft, Capitol DC, 96 ft/ Base of dome 23 ft thick, at oculus, 2 ft thick/Pantheon, Rome cross-section showing spherical design/APR 29, 2002