OSTIA ŏs’ tĭ ə (Lat. ostia, mouth). A town located at the mouth of the Tiber River.
Rome was built on the banks of the Tiber River, approximately sixteen m. from the seacoast, for reasons of security and trade. As the city grew the need for access to the sea became apparent, and Ostia was settled at the mouth of the river sometime between 350 and 300 b.c. During the 2nd Punic War (218-201 b.c.) it served as a naval base, and upon the conclusion of peace developed into an important commercial center. Since Rome depended for its grain supply upon imports from Sicily and Africa, Ostia was of vital significance to the city.
During the 1st cent. a.d. the city developed steadily as trade increased, and various emperors improved it by building a new harbor and other public facilities; e.g., Caligula constructed an aqueduct to supply the city with fresh water. By the 2nd cent. the city was at its height: ships anchored in its harbor from Africa and the E, and it was adorned with as many as six public baths, a theater, and possibly an amphitheater.
Ostia is important for the religious, cultural, and social knowledge of the Rom. people. Over 6000 inscrs. have been found dealing with all phases of Rom. life. Such a town is necessarily cosmopolitan in nature, and its religious life reflected this. The patron god was Vulcan, but various cults from the E were found, e.g., the worship of Isis and Magna Mater. Mithraism also had its place. There are no clear traces of Christianity in Ostia until about the year 200, but by 250 the town had a bishop.
Beginning with the 3rd cent., decay set in, and Ostia was harrassed continually by Goths, Huns, and Saracens in turn. Malaria became prevalent and finally made the site uninhabitable. As usual in such cases, the place became a quarry for the builders of the middle ages, and even up to the 19th cent. Systematic excavation of Ostia began in 1909, and has been carried on sporadically ever since. Much of the ancient city can be seen by tourists today.
Oxford Classical Dictionary; Pauly-Wissova, Real-Encyclopädie der classischen Altertumswissenschaft, XVIII2, 1654-1664.