• The pantheon was built by Agrippa (27 BC), restored by Domitian and Trajan, and rebuilt by Hadrian (117-138)

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• With the advent of Christianity, Theodosius closed the temple (391) and Phocas gave it to Pope Boniface IV who made it into a church (609). As Boniface had 28 carts of martyrs' bones brought from Rome's cemeteries for the dedication, it was called S. Maria ad Martyres

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• The building's diameter is equal to its height at about 142 feet. In the walls there are seven large niches which were probably dedicated to the seven planetary gods