Because of its peculiarities, Castel Sant’Angelo can be considered a monument, an archaeological area and a museum at the same time. The building had an extremely varied use throughout its complex history: erected as an imperial mausoleum, it later became a fortified residence, a prison and finally a monument-museum.

Built in the 2nd century A.D. at the behest of the Roman emperor Hadrian as a funeral mausoleum for himself and his family, the monument – henceforth known as the Mole Adriana – was later included in Rome’s city walls and transformed into a sort of fortress for the city’s defence, acquiring the appellation castellum. In the early Middle Ages, the name of sancti Angeli was added to the legend according to which, in 590, Pope Gregory the Great had a vision here of the archangel Michael sheathing his sword, symbolising the end of the pestilence that afflicted the city.

Its proximity to St. Peter’s, its strategic position and its closed and imposing bulk made Castel Sant’Angelo the centre of political interests, inextricably linking its fate to that of the Church ever since the keys of the building were handed over to Pope Urban V in 1367 to urge his return to Rome from exile in Avignon.

Since then, numerous architectural interventions have been carried out to, on the one hand, strengthen its defensive structure with the construction of ramparts and pentagonal walls, and, on the other hand, to make it an increasingly magnificent papal residence, experiencing its greatest splendour under Paul III Farnese (1534-1549).

Starting in the 17th century, Castel Sant’Angelo gradually lost its role as a papal residence to become almost exclusively a political prison. It became part of the Italian State property in 1870 as a military prison and barracks, and became a National Museum in 1925: at that time extensive work had already begun on the reorganisation and restoration of the site, the acquisition of works and collections, and the fitting out of various rooms.