The bouleuterion, or Council House, one of the most ancient and important buildings of the sanctuary of Olympia, was the seat both of the Elean Senate, whose members were responsible for the organisation of the games, and possibly of the hellanodikai, or umpires. This is where the athletes registered and drew lots, and where their names and the program of events were announced. It was also where any offences and pleas were tried, and where penalties were decided. Situated south of the temple of Zeus, outside the sacred precinct of the Altis, the building was begun in the sixth century BC and completed in the fourth century BC; small additions and changes were made in the Roman period.

The bouleuterion consisted of a square hall flanked north and south by two oblong apsidal wings of roughly equal size and plan. The north wing (30.65 metres long and 13.78 metres wide) was built in the sixth century BC and the south wing a century later. Each wing had a central row of seven columns and a cross-wall cutting off its apse; each apse was divided into two by a central wall. The official Elean archives containing the names of all the Olympic victors may have been kept here. A hall, fourteen metres square, possibly open to the sky, was added between the two wings. Inside were the altar and statue of Zeus Horkeios; the god held thunderbolts and was portrayed with a menacing face. Here, according to Pausanias (V, 24, 9), competitors, their relatives and their trainers swore that they would be guilty of no foul play in the games, and judges swore that they would be fair and would not accept bribes. During this procedure athletes and judges stood on wild boars' genitals. An inscription at the statue's feet contained curses and penalties for the perjurers. In the fourth century BC, an Ionic portico of twenty-seven columns was built along the whole length of the east fa?ade, connecting the three buildings. In front of the Ionic portico is a trapezoid colonnaded court of Roman date, consisting of three Doric stoas (north, east and south).

Only the building's foundations have survived. There has been limited restoration and the area around the monument and between the two wings has been planted with trees.