Hop on the commuter train at Lido Station (next to the Piramide Metro stop) and make the 25-minute trip to Ostia Antica, Rome’s ancient port town and administrative center. The teeming city of up to 100,000 residents is relatively well preserved and allows visitors a peek into the daily life of ancient Romans. Walk the basalt streets, visit the Forum, descend into Mithraic sanctuaries, and peruse the market stalls, which were in use until around the 5th century C.E.