Castel Sant'Angelo with a Live Guide, Arrive Twenty Minutes Early

A guided visit with skip-the-line entry, and one instruction that is worth following literally: be at the meeting point twenty minutes before the start. Check-in and the security screening take that long, and a group cannot wait. Once inside, the guide works through a building that has been watching the Tiber for nearly two thousand years and has changed job repeatedly. Hadrian built it as his mausoleum. It became a papal palace, a prison and a military strongpoint, and each occupant left something structural behind: chambers, ramparts, fortified corridors that turn corners for defensive reasons. The Passetto di Borgo is part of that system, the raised passage running to the Vatican, and it carries the best stories in the building, most of them about people leaving in a hurry. The route ends on the upper terrace, where the view is a full circle: the Vatican and the dome of St Peter's on one side, the river below, the historic centre on the other. The coordinator waits in front of the main entrance with a blue flag.