National Museum of Castel Sant’Angelo Rome The National Museum of Castel Sant’Angelo, also known as the Musoleum of Hadrian, is an iconic fortress located on the banks of the Tiber River in Rome, connected to the Vatican via the Passetto di Borgo. Built between 123 and 135 AD, it has undergone many transformations over the centuries, also serving as a prison of the Papal States. Currently owned by the Italian State and managed by the Direzione Musei statali di Roma, it continues to attract millions of visitors every year.