"St. Angels Castle" was erected in 139 AD by the emperor Adriano who built this mausoleum for himself and his successors.It has a rectangular shape and is topped by a cylindrical construction, surmounted by a circular temple.In the Middle Ages it became a military citadel, from which on one occasion the besieged Romans burled even statues at the enemies.Its initial funeral function was thus soon lost, ylelding to that of a castellum in 550, during a papal procession to fight the plague, the Archangel Michael was seen gliding above the castle while sheathing his sword, the symbol of the plague On that occasion a chaepel was built on the top of the fortress, which was then called Sancti Angeli ("of the St. Anger").The popes used the edifice as a residence, especially as a place of defence of the Vatican, moreover as the seat of the archives and the Pontifical treasure It was used as a jail from the 19th century on 1be eclectic story of this monumental edifice is illustrated in the rooms of the museum.From the terrace you can enjoy splendid view of the city.