Ostia (ancient world)

A city on the coast of Latium (Lazio), western Italy, at the mouth of the river Tiber, sixteen miles from Rome

When the Romans began a modest enlargement of their territory in the regal period, they seem to have expanded as far as the coast, establishing the port of Ostia at the mouth of the Tiber in order to exploit adjoining salt beds. This event was attributed to the semi-legendary King Ancus Marcius (traditionally 642–617 BC), but may instead be tentatively ascribed to Servius Tullius (c 578–535). Archaeological investigations have so far failed to reveal any trace of so early a settlement, but that may only be because the habitation center in question was located on ground which it has not been possible to explore.

At the time when the Romans broke up the Latin League c 338, they also regularized and strengthened whatever settlement they already possessed at Ostia, founding one of their very first colonies on the site. Its three hundred Roman citizen families inhabited a rectangular fort covering five acres, designed like a camp with two geometrically planned intersecting main streets and a strong stone wall, which the male settlers were numerous enough to man if they stood six feet apart. The colony's primary function was to defend the Tiber mouth from maritime enemies and pirates, thus removing the need for a permanent Roman fleet. But although the harbor at the mouth of the delta-forming river was still very inadequate, Ostia also supervized the collection of salt (see above), regulated trade, exacted customs dues, and stored grain and other foodstuffs for transportation by road or river up to Rome.

The First and Second Punic Wars (264–241, 218–201) caused Rome to develop its fleet, so that Ostia became an important naval base. When the wars had been successfully concluded, the impetus to maintain such a navy weakened, but the growth of Rome's population caused Ostia to retain its importance as a supply port for purchases from overseas, especially grain. By 100 BC the original small stronghold had become a substantial town, possessing an improved harbor and surrounded by walls enclosing a much increased perimeter. During the civil wars between Marius and Sulla, the former, returning from Africa, captured Ostia before marching on Rome (83).

The earliest surviving temple in the town, dedicated to Hercules, dates from about this time, but its important cult was dedicated to Vulcan, whose priest was the principal religious authority of the city. Ostia was plundered by pirates c 68, and during the wars between Octavian (the future Augustus) and Sextus Pompeius (concluded in 36) the place was imperilled by Sextus' command of the Tyrrhenian sea. Its revival under the Augustan peace is reflected by Agrippa's construction of a permanent theater, adjoined by a commercial meeting place. At the end of the forum a Capitolium was built, and cults of the Dioscuri (Castor and Pollux), Venus, Ceres, Fortuna and Spes (Hope) are of Augustan or earlier origin.

Since, however, the harbor was too small to handle all the ships that now sought entry and the larger of them could not pass the sand bar at the river mouth, Claudius (AD 41–54) constructed a large artificial port two miles to its north, equipped with a towering lighthouse and linked to the Tiber by two canals. Since, however, it soon became clear that this new harbor did not provide sufficient shelter against sudden storms (one of which sank two hundred ships in 62; and now a number of merchant vessels have been found on the seabed), Trajan (98–117) added an inner hexagonal basin, excavated from the coastline, which solved the problem and caused Ostia's activity and prosperity to reach its peak.

A direct result of this efflorescence was a major reconstruction of the city. The most remarkable feature of this new urban development was the type of private housing required to meet the increase in population. The characteristic dwellings of second century Ostia (superseding atrium houses similar to those at Pompeii and Herculaneum, though villas of that type continued to be built on the seashore) were apartments normally four and sometimes five storeys high. They were built of concrete-cored brick; stone was employed to decorate windows and doors, and external architectural details were sometimes picked out with red paint. The exteriors also displayed balconies or continuous terraces, projecting over timber or stone corbels. Roofs were generally sloping and tiled, though occasionally flat. Occupied, in certain cases, by more than one family, the apartments often comprised five or six rooms, with the largest at the end, served by a corridor overlooking the street. Each apartment had its own separate staircase of travertine or brick, with wooden treads, rising either from the street (between ground-floor shops) or from interior courtyards. Walls and ceilings in the apartments were sometimes attractively painted, and floors had mosaic pavements. Yet selenite (glass) was only rarely used in windows, for which wooden shutters were usually the only coverings; and although by this time, in the Roman world, water was piped to many private houses, it did not reach these blocks. Certain groups of them, however, shared a communal bath house, and possessed a garden in common.

The city also obtained three new sets of public baths (one of which was paid for by Hadrian [117–38] and Antoninus Pius [138–61]) and a theater. Other aspects of Ostian life were represented by bars and wineshops, bakeries, new types of shops including impressive business premises, and public warehouses (horrea) used for the storage of larger quantities of grain (sometimes in huge sunken jars) before transportation upstream to Rome. Meanwhile the commercial quarter of the city, adjoining the theater, was transformed into what has been interpreted—despite some dissent—as the Square of the Guilds (Piazzale del Corporazioni) containing, according to this interpretation, seventy offices of commercial associations, ranging from workers' guilds to corporations of foreign representatives from all over the ancient world. Religious buildings included a new Capitolium, probably erected by Hadrian. But by this time foreign cults, notably those of Cybele, the Great Mother, and then the Egyptian Isis and Serapis, had taken deep root, and in the latter half of the second century Mithraism also became popular, eventually possessing no less than fifteen chapels. A large synagogue, too, has now been discovered.

In the following century emphasis shifted to the harbor quarter inaugurated by Claudius and Trajan, which under Constantine I the Great (306–37) assumed an autonomous entity of its own under the name of Portus, or Civitas Flavia Constantiniana Portuensis. Meanwhile the city of Ostia itself had become much more a residential center than a trading town; the big apartment houses were allowed to go to ruin, but the construction of lavish new private houses went ahead. Christianity was battling forcibly with Mithraism, and Constantine was said to have endowed an Ostian basilica dedicated to St. Peter and St. Paul. The building tentatively recognized as this church is in reality a guesthouse, but a smaller church and Christian hall have come to light; the latter shows signs of violent destruction. St. Augustine stayed at Ostia with his mother Monica before returning to north Africa.

Portus was sacked by Alaric's Visigoths in 408. Yet c 425 a new marble colonnade was built, extending for two hundred yards along the canal; it was known as the Porticus Placidianus (after Placidius, one of the names of Valentinian III). In the following century, however, not only was Ostia chronically vulnerable to marauding enemies, but its harbor was silting up; and, besides, overseas grain was no longer needed for Rome's greatly reduced population.