2 Best Sights in Ostia Antica, Side Trips from Rome

At its peak, the ancient port town at this site was home to a cosmopolitan population of rich businessmen, wily merchants, sailors, slaves, and their respective families. Great warehouses were built here in the 2nd century AD to handle goods that passed through, notably huge shipments of grain from Africa. Indeed, the port did so much business that it necessitated the construction of insulae (apartment buildings) to provide housing for the city's growing population.

The increasing importance of nearby Portus and the inexorable decline of the Roman Empire eventually led to the port's abandonment. In addition, the coastline retreated over the millennia, and a 16th-century flood diverted the course of the Tiber. Tidal mud and windblown sand buried the ancient port town until the 19th century, when it was extensively excavated.

You can wander through the massive archaeological site and explore its curious corners, mosaic floors, fallen columns, and huge Roman amphitheater. The on-site Museo Ostiense displays sculptures, mosaics, and objects of daily use found here. There's also an on-site cafeteria. The recently excavated ports of Tiberius and Claudius are nearby and also well worth visiting.

The distinctive castle, easily spotted as you come off the footbridge from the train station and part of the medieval borgo (old town), was built in 1483 by the future Pope Julius II when he was the cardinal bishop of Ostia. The structure's triangular form is unusual for military architecture, but it was strategically placed for defense when the Tiber River still flowed below its walls. After crossing a drawbridge to gain access the castle's interior, you'll find a small exhibit of historical sketches on the second floor.