The name comes from the greek word stadion, distance (around 180 metres) along which took place the most impor¬tant among the greek competitions: the race. Domitian’s Sta¬dium had a circus form with parallel long sides, a curved short side and the other one slightly oblique; it measured around 275 per 106 metres. The building, only example of masonry stadium known outside Greek World, was made in travertine blocks and brickwork; the external front was characterized by two different arcade orders resting on pilasters with semi-co¬lumns. The main entrances, in the middle of the long sides and of the hemicycle, were characterized by an arcade with marble columns. The steps for the public were divided into overlying sectors (maeniana) and it has been calculated that it could host until 30.000 people.
In 1936, when the houses built on the curved side of the Sta¬dium were demolished, it was possible to uncover a portion of the cavea, where one of the main entrances was located. The archaeological finds retrieved during the excavations and on display here include numerous sculpture fragmen¬ts and a Pentelic marble torso, a copy of the 4th century BC Apollo Lykeios by Praxiteles. Other remains of the Sta¬dium have been identified in many Piazza Navona basemen¬ts; alongside the well-known relics under the church of St. Agnese, others are located underneath the buildings of the École Française de Rome.