In short
Rome is walked. The historic centre fits within a three-kilometre perimeter, and the whole city is World Heritage listed along with the properties of the Holy See.
The centro storico — Pantheon, Navona, Trevi — is dense and saturated. Trastevere, across the Tiber, is the evening quarter. Monti, behind the forums, is quieter and well placed. Testaccio is working-class and is the home of Roman cooking. Prati, near the Vatican, is residential and well-heeled.
Arriving and getting around
Two airports. Fiumicino is linked to Termini by the Leonardo Express in thirty-two minutes, non-stop. Ciampino has no train: bus shuttle only.
Termini is the central station and the junction of the two métro lines.
The métro has only three lines and serves the historic centre poorly, for a simple reason: you cannot dig without hitting remains. Buses and walking remain the real modes.
What it really costs
Rome is expensive near the sites and reasonable two streets away. Testaccio and Pigneto serve Roman cooking at local prices.
The coperto, a per-person cover charge, must be shown on the menu. A restaurant presenting a tourist menu in four languages next to a monument is charging passing-trade rates.
When to come
April–May and September–October. July and August are scorching and many neighbourhood restaurants close in August.
Entry to the Vatican Museums, the Colosseum and the Borghese Gallery is booked by time slot, sometimes weeks ahead. The Borghese imposes a two-hour slot and a strict quota.
What nobody tells you
On Sundays many central streets are closed to traffic, and the ZTL — limited traffic zones — govern access by car all week, with automatic fines.
The water from the nasoni, the hundreds of cast-iron fountains with a curved spout, is drinkable, cold and free. Blocking the spout with a finger turns the jet into a drinking fountain.
The major basilicas require covered shoulders and knees, checked at the door, including in forty-degree heat.