The Pantheon (UK: /ˈpænθiən/, US: /-ɒn/; Latin: Pantheum, from Ancient Greek Πάνθειον (Pantheion) '[temple] of all the gods') is an ancient 2nd century Roman temple and, since AD 609, a Catholic church called the Basilica of St. Mary and the Martyrs (Italian: Basilica Santa Maria ad Martyres) in Rome, Italy. It is perhaps the most famous, and architecturally most influential, rotunda.
The Pantheon was built on the site of an earlier temple, which had been commissioned by Marcus Vipsanius Agrippa during the reign of Augustus (27 BC–AD 14). After the original burnt down, the present building was ordered by the emperor Hadrian and probably dedicated c. AD 126. Its date of construction is uncertain, because Hadrian chose to re-inscribe the new temple with Agrippa's original date inscription from the older temple.