The Mausoleum of Hadrian, usually known as the Castel Sant'Angelo is a towering cylindrical building in Rome, initially commissioned by the Roman Emperor Hadrian as a mausoleum for himself and his family. The building, located in the rione of Borgo, spent over a thousand years as a fortress and castle, and is now a museum. It was erected on the right bank of the Tiber, between 135 and 139.
