The Rome–Lido railway, branded as Metromare, is an urban railway line connecting the Porta San Paolo Station in Rome to Lido di Ostia, Rome's seaside neighborhood. The railway is 28.3 km (17.6 mi) long, stops at 13 stations and carries on average over 90,000 passengers per day.

Ostia is a large neighbourhood in the Municipio X of the comune of Rome, Italy, near the ancient port of Rome, which is now a major archaeological site known as Ostia Antica. Ostia is also the only municipio or district of Rome on the Tyrrhenian Sea, and many Romans spend the summer holidays there. Therefore it's entirely situated within the Municipality of Rome and is the city's seaside resort.