Castel Sant’Angelo is a monument and a tourist spot in Rome, on the right bank of the Tiber opposite the bridge Aelius (current bridge Sant’Angelo), close to St. Peter’s Basilica in the Vatican, in the district of Il Borgo; Castel Sant’Angelo is connected to the Vatican by the fortified corridor “Passetto”. The castle was radically altered several times during the Middle Ages and the Renaissance.
Initiated by the Emperor Hadrian in 125, inspired by the Mausoleum of Augustus, it was completed by Antonino Pio in 139.
Since 403, with the emperor Honorius, the building lost its original function and becomes a fortress for the defense of Rome with the name of Castellum for the first time.