Ostia: Roman city, next to the port of ancient Rome.
- Situated at the mouth of the river Tiber, about thirty kilometers downstream from Rome
- According to legend, built by king Ancus Martius, and it may indeed be true that Rome already was in control of the estuary of the Tiber at an early stage
- Salinae, port (originally just the beach and the river), trade center, transshipment
- A colonia civium Romanorum in 350 VC
- Naval base during the First and Second Punic Wars
- Later especially important for merchant vessels carrying food from Sicily and Africa
- During the reign of the emperor Augustus (r.27 BCE - 14 CE), his right-hand man Agrippa built the theater
- The emperor Claudius (r.41-54) built two large piers, which extended into the sea and offered protection to the many merchant ships. This port was three kilometers north of Ostia itself. Inaugurated by Nero (r.54-68). This port was called Portus Augusti.
- Another expansion: the hexagonal port of Trajan (r.98-117)
- Suetonius occupied two priestly functions (flamen sacerdotalis and pontifex Volcanalis).
- Cemetery between Portus Augusti and Ostia itself
- Augustine and his mother Monnica lived here. Monnica was buried in Ostia; her epitaph survives
- 455: Used by the Vandals as base for their attack on Rome
- Still occupied in the sixth century CE but abandoned in the early Middle Ages
- Many houses with several floors (e.g., Casa di Diana)
- Three public baths
- Sanctuaries, synagogue, genizah, temple of Mithras
- Barracks of the vigiles
- Granaries ("horrea")
- Famous: the Piazzale delle corporazioni, with black-and-white mosaics in the offices of the merchants