According to ancient sources, Ostia Antica, was founded by King Ancus Marcius in the second half of the seventh century BC, but subsequent research carried out, however, dates the oldest part to a later period.
The oldest nucleus that we know of the city of Ostia consists of the “castrum“: a primitive maritime citadel, fortified in accordance with the typical military layout of the time, normally, as here, rectangular in shape.
The settlement was built in the period after the destruction of Veio (396 BC), to meet military and commercial needs.
The “castrum” of Ostia was thus an outpost, where the fleet had to assure control of the traffic routes that passed along the mouth of the Tiber.
Next to the “castrum”, there are the remains of nine religious buildings dedicated to eastern faiths (mithraeums, the temples of Isis, of Serapis, of the Magna Mater, [Cybele] and of the Bona Dea [fertility goddess]) and the first Jewish synagogue; thermopolia [hot takeaway shops], bath-houses, taverns, shops and inns, as well as large amphitheatre.
Among the sites worth visiting: the numerous thermal establishments, the firefighters’ barracks, the Theatre with adjoining Square of the Guilds, the House of Apuleius, the House of Diana, the Forum with its Capitol; the various temples, the Houses of the Dioscuri [Castor and Pollux], of the Nymphaeum and of the Round Temple. The huge Theatre (107 m. long, 78 m. wide), a venue for shows and concerts in the summer, is one of the highlights of a visit, as is the Square of the Guilds.
The Ostia Antica Museum, with its fascinating exhibits of items unearthed in excavations, is a must.