The Pantheon is a former Roman temple and, since AD 609, a Catholic church in Rome, Italy. It was built on the site of an earlier temple commissioned by Marcus Agrippa during the reign of Augustus, then after that 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 not to inscribe the new temple but rather to retain the inscription of Agrippa's older temple.

Ancient Roman temples were among the most important buildings in Roman culture, and some of the richest buildings in Roman architecture, though only a few survive in any sort of complete state. Today they remain "the most obvious symbol of Roman architecture". Their construction and maintenance was a major part of ancient Roman religion, and all towns of any importance had at least one main temple, as well as smaller shrines. The main room (cella) housed the cult image of the deity to whom the temple was dedicated, and often a table for supplementary offerings or libations and a small altar for incense. Behind the cella was a room, or rooms, used by temple attendants for storage of equipment and offerings. The ordinary worshiper rarely entered the cella, and most public ceremonies were performed outside of the cella where the sacrificial altar was located, on the portico, with a crowd gathered in the temple precinct.