The Mausoleum of Hadrian, today’s Castel Sant'Angelo, is the grandiose dynastic tomb that Emperor Hadrian built on the banks of the Tiber river, starting from 130 AD; it was completed in 139 AD, one year after his death.
After the battle of Hadrianopolis in 378 AD, when the emperor Valens was defeated and killed by Alaric's Visigoths, the pressure of the barbarians on Italy became increasingly threatening. The emperors Honorius and Arcadius raised and strengthened the Aurelian walls in Rome, building new towers, and the Mausoleum was included in the walls, becoming the most important defensive stronghold on the right bank of the Tiber.
In 410 AD there was the first major sack of the city, by the Visigoths, followed by that of the Vandals in 455 AD. In both cases the barbarians failed to conquer the Mausoleum, but camped around it, creating a settlement which would later become the Borgo, and from there they devastated the whole city.
In 537 AD Rome was attacked by the Goths of Vitiges,
and under the leadership of general Belisarius the Mausoleum once again resisted the siege.
In his De Bello Gotico (On the Gothic War) of 550 AD, the Byzantine historian Procopius of Caesarea
recounts that during the siege the ancient statues still remaining on the site were torn to pieces to throw them at the enemies:
«Meanwhile the Goths launched the attack on the Aurelian gate and at Hadrian's Mole,
without any machinery, but equipped with a very large number of ladders and ropes, convinced that they would easily reduce the enemies to impotence and without effort conquer the few men garrisoned there...
Because the garrison could not use the so-called ballista (these machines do not throw the darts except from the front)
, nor could they do anything with the arrows against the attackers...
The Romans were dismayed, having no hope of finding a defense that would save them; but then by common consent they broke the majority of the statues, which were very large, and lifting those very large stones with both hands, they thew them at the enemies
: and those thus struck retreated».
Having lost its function as a dynastic tomb and being transformed into a stronghold, the Mausoleum of Hadrian took the name of Castel Sant'Angelo during the terrible plague of 590 AD, when pope Saint Gregory the Great (590-604 AD) led a penitential procession to bring in Saint Peter’s Basilica the image of Maria Salus populi Romani, preserved in the basilica of Santa Maria Maggiore.
When the procession approached the Aelius Bridge, pope Gregory suddenly heard the voices of the angels, looked up, and on the top of the Castle the Archangel Michael appeared to him, cleaning the blood from his sword and placing it back in the sheath: a divine sign that the plague was over.
At the end of the fifteenth century Pope Alexander VI Borgia (1492-1503) had a deeper external moat dug around the Castle. On that occasion fragments of ancient sculptures and decorations were found,
which are of colossal dimensions and must be those cast on the Goths by the defenders of Belisarius.
Those sieges are part of the thousand-year history of the Mausoleum, which is explained in detail with plans and photographs in Marina De Franceschini’s forthcoming book «The Mausoleum of Hadrian. Castel Sant'Angelo. Architecture and Light».