Two days covers Rome's greatest hits, but it is a highlights rush and you will feel it, because Rome really needs three. In 48 hours you can do ancient Rome (Colosseum, Forum, Palatine) on day one and the Vatican plus the piazza core (Pantheon, Trevi, Navona) on day two, with dinner in Trastevere both nights. What you must cut: the Galleria Borghese, Villa Borghese, Castel Sant'Angelo interiors, Testaccio's food, and any slow lingering, so this is a march, not a stroll. It suits a weekend break, a stopover, or a first taste before combining with Florence. The non-negotiables: pre-book the combined Colosseum-Forum ticket and the Vatican 8am slot before you fly, or you lose hours to queues you cannot afford on a two-day trip. Base yourself in Centro Storico so both mornings start on foot and the evenings put you steps from dinner. If you get a third day, add the Borghese and slow down, it is the single best upgrade.