Ancient city, Ostia Ancient is now a vast archeological site, located just 19 miles (30 km) West of Rome and the River Tiber. The town was abandoned and buried for ten centuries until it was rediscovered. It was one of the most thriving cities in the region, thanks to its status as Rome's harbor city. However, after the collapse of the Empire, the city fell into decadence, and it was eventually abandoned and remained untouched and magnificently preserved for centuries. Ostia Antica became Rome's main seaport during the Roman Republic (509 BC - 27 BC) and the city was largely enhanced by Julius Caesar and Tiberus during the Roman Empire. Nevertheless, the Romans slowly began to depend on other ports, meaning that the commercial activity in Ostia slowed down until it degenerated into decay during the IV century AD.