| This castle was built by the Emperor Hadrian (117-138) 
              as a mausoleum for himself and his successors and was completed 
              in 139 A.D. by Antonius Pius. According to a legend during a procession 
              led by Pope Gregory the Great in 590 to pray for the end of the 
              plague, an angel appeared on the top of the mausoleum in the act 
              of putting his sword back in its sheath, which gesture was interpreted 
              as a divine sign of the end of the plague. In remembrance of the 
              miracle, a chapel was built on the mausoleum and on top of the Castle 
              was also placed a statue of the Archangel Michael. Since then, it 
              has had many roles: as part of Emperor Aurelian’s city wall, 
              as a medieval citadel and prison, and as the residence of the Popes 
              above, a 58 rooms museum covers all aspects of the castle’s 
              history.  |