Pantheon, a temple or other sacred building dedicated to all gods. The most famous is the Pantheon in Rome, built B.C. 25 by Augustus minister, Agrippa. It is a circular domed structure with an octastyle portico of Corinthian columns Since 607 it has been used as a Christian Church, being dedicated to the Virgin Mary and all the martyrs. It is one of the finest and best preserved relics of antiquity.