Church in Rome

The largest church in the world, and the reason most itineraries give the Vatican a morning of its own. Free to enter with a long security queue; the dome climb is separate, paid, and gives the definitive view over the square and the city. Shoulders and knees must be covered — enforced at the door, without exception, in any weather.

A Roman temple that has been in continuous use for nearly two thousand years, with the largest unreinforced concrete dome ever built and a nine-metre hole open to the sky. Ten minutes inside is enough to be worth the trip, which makes it the easiest thing in Rome to fit into a day. Rain falls through the oculus onto a sloped, drained floor.