When should I visit Rome, Italy, for the best experience?

The Colosseum runs on a seasonal timetable rather than fixed hours, and the steps in it are useful planning information. From 2 January to 15 February it opens 8.30am to 4.30pm with last entry at 3.30pm. From 16 February to 15 March it runs 8.30am to 5pm with last entry at 4pm. From 16 March it extends again to 5.30pm. In practice, an early-March visit buys an extra ninety minutes of site time over an early-February one at the same admission price, and the shift happens before the crowds do.

Rome's other defining visit has a monthly rhythm worth building a date around. The Vatican Museums open 8:00am to 8:00pm Monday to Saturday with last entry at 6:00pm, and on the last Sunday of each month they open 9:00am to 2:00pm with last entry at 12:30pm and free admission. That is the one day a month the Sistine Chapel costs nothing — and also the shortest day the museums run, with guided tours requiring a reservation.

The historic core itself is a single UNESCO property, inscribed in 1980, which is why so much of what you want is inside walking distance of the rest. The inscription is unusually constructed: it covers the Historic Centre of Rome together with the properties of the Holy See in the city that enjoy extraterritorial rights, and the basilica of San Paolo Fuori le Mura, which sits well outside the old walls.

The free last Sunday at the Vatican Museums closes at 2:00pm with a 12:30pm last entry — five hours rather than the usual twelve, for a site people routinely allot a full day. Pairing it with a Colosseum slot the same afternoon only works in the months when the archaeological park is open past 5pm, which is to say from mid-March onward rather than in January and February.

• Early spring — From 16 March the Colosseum runs to 5.30pm, and the Vatican Museums are already on their 8:00am-to-8:00pm weekday schedule.
• A last Sunday — Free Vatican Museums entry, 9:00am to 2:00pm, last entry 12:30pm; arrive for the opening or not at all.
• Deep winter — A 4.30pm close and a 3.30pm last entry at the Colosseum between 2 January and 15 February shortens the day considerably.

Two dates remove the Colosseum entirely: it is open daily except 1 January and 25 December. The free Vatican Sunday is the museums' busiest and shortest opening of the month, so it is a saving rather than a comfortable visit. And because the 1980 inscription includes San Paolo Fuori le Mura outside the walls, a plan that treats "the historic center" as one walkable unit will leave part of the designated property unvisited.

The Rome things-to-do question in this group covers ticket prices, the Colosseum's compulsory reservation rule and the criteria behind that UNESCO inscription.