View of Rome from the Castel Sant'Angelo. In the background: Saint Peter's basilica (Vatican).- The Castel Sant'Angelo (Castle of the Holy Angel; Chateau Saint-Ange; Die Engelsburg ) is a towering cylindrical building in Rome.- Construction: 123-139 AD; commissioned by the Roman Emperor Hadrian as a mausoleum for himself and his family.(Mausoleum of Hadrian; Mausol閑 d'Hadrien; Mausoleum des Kaisers Hadrian; Mausoleo di Adriano). The building was later used by the popes as a fortress and castle; and is now a museum. (Museo Nazionale di Castel Sant'Angelo)Rome; Italy. 2020.