With so many sights, attractions, and cities, deciding where to go on your day trip to Rome can be difficult. For a quick excursion, hop on the train to Hadrian's Villa, Villa d'Este, Ostia, or Caserta Palazzo Reale (they're all located under an hour from the city center). If you have more time on your hands, you can instead explore a larger Italian city for a day, like Florence or Naples.