The Rome IndexCastel Sant'Angelo
A Roman emperor's mausoleum turned papal fortress, with one of the city's best river views.
What it was
Originally built as Emperor Hadrian's mausoleum, the building was later fortified and connected to the Vatican by a raised secret passage, the Passetto di Borgo, used by popes fleeing danger.
What to see
Papal apartments, a weapons collection, and a rooftop terrace with sweeping views up and down the Tiber — genuinely one of the best panoramas in the city, and less crowded than other viewpoints.
Getting there
A flat, scenic walk from the Vatican along the river, making it an easy pairing with a Vatican Museums morning.