The Prytaneion, one of the oldest and most important buildings at Olympia, was the administrative centre of the sanctuary's political life and of the Olympic Games. It was the seat of the magistrates, the high officials who oversaw the sacrifices performed monthly to honour the gods; Pausanias (V, 15, 8) refers to it as the 'Prytaneion of the Eleans'. The Prytaneion occupied the north-west corner of the sacred enclosure, directly opposite the gymnasium. It dates in some form to the late sixth or early fifth century BC, but was repeatedly remodeled and enlarged later.

The building was a square of 32.80 metres with an entrance on the south side and a vestibule leading into a central chamber, 6.80 metres square. This chamber contained the sacred hearth of the Eleans, where a fire burned day and night. According to Pausanias, the hearth was made of ashes and the ashes produced by this eternal fire were transported to the altar of Zeus which thus grew bigger all the time. The dining room where the Olympic victors were entertained by the Eleans is thought to have been located either in the west or north wing. Inside the Prytaneion, on the right of the entrance, was an altar of Pan.

The Prytaneion is closed to the public.