Castel Sant'Angelo is one of Rome's most recognisable landmarks, a massive cylindrical fortress overlooking the Tiber. Built in the second century as a mausoleum for Emperor Hadrian, it later became a military stronghold, papal refuge and prison. Today, its layered history is preserved in a museum just across the angel-lined Ponte Sant'Angelo.
The climb through the castle is a journey through those different lives: ancient Roman masonry gives way to defensive ramparts and richly decorated papal apartments. A covered passage, the Passetto di Borgo, connects the fortress to the Vatican and famously sheltered Pope Clement VII during the Sack of Rome in 1527. At the top, a bronze Archangel Michael crowns the building, recalling a legend that gives the castle its name.
The rooftop terrace is a highlight, with sweeping views across Rome towards St. Peter's Basilica and the bend of the Tiber. Book tickets online in advance to reduce time spent queuing, and aim for opening time or late afternoon to avoid the busiest, hottest hours. Expect ramps and stairs on the way up; if you're interested in the castle's many transformations, an audio guide can help bring the rooms to life.