Three days in Rome will not give you the city — nothing short of a year really does — but it is enough to see the headline acts and leave with a feel for the place. This itinerary is built around walking distances and pacing: every day starts with the heaviest sightseeing and ends in a neighbourhood you'd actually want to linger in.
Day 1 — Ancient Rome
Start at the Colosseum first thing — the line builds fast even with skip-the-line tickets. From there, walk straight into the Roman Forum and up Palatine Hill (one combined ticket). Lunch in Monti, the neighbourhood directly behind the Forum, then a slow afternoon at the Capitoline Museums. Finish the day with dinner near Piazza Navona.
Day 2 — Vatican City and Trastevere
Vatican Museums opening time is the only reasonable option in season. Book an early-access tour if budget allows — the Sistine Chapel is unrecognisable when it isn't packed. After the Vatican, walk south to Trastevere for lunch and an afternoon of wandering. Don't plan an evening — Trastevere does that for you.
Day 3 — Galleries, gardens and last bites
Start at the Galleria Borghese (timed entry, book days ahead) and walk it off in the Borghese Gardens. Cross to the Spanish Steps, browse Via dei Condotti, then end with a long lunch in the Pantheon district. If you have energy left, the Trevi Fountain at dusk is genuinely worth the crowds.
Where to base yourself
Three days is too short to commute. Stay inside the historic centre — Monti, Centro Storico or Trastevere. You'll walk to nearly everything on this itinerary.
Day trips if you have a 4th day
Pompeii by high-speed train is doable in a day. Tivoli (Hadrian's Villa and the Villa d'Este gardens) is a half-day. Both are an easy add-on if your flight isn't until late evening.
