Castel Sant'Angelo was originally built as a mausoleum for Emperor Hadrian in the 2nd century but it has been used for many different purposes since then. A fortress for besieged popes in the Middle Ages, an aristocratic residence and then a prison, Castel Sant'Angelo is now a museum dedicated to its own history. The view of St. Peter’s Basilica is phenomenal. The Ponte Sant’Angelo, leading to the castle, dates back to Hadrian’s time; it was updated by Bernini.