Ancient Roman town.
Originally at the mouth of the Tiber River , it would now be about 4 mi (6 km) upstream. The modern seaside resort of Ostia, Italy, is near the ancient city. It was probably founded in the 4th century BC and developed as a naval station, major port, and centre of the grain trade. It reached the height of its prosperity in the 2nd century AD, when it had a population of about 50,000. It suffered from the decline of the Roman economy in the 3rd century and from barbarian raids in the 5th century. Its Roman ruins were quarried for building materials in the Middle Ages and for sculptors' marble during the Renaissance. Excavations began in the 19th century, and about two-thirds of the Roman town can now be seen.