The Passetto di Borgo: Pope Nicholas III (pape Nicolas III) connected the castle to the Vatican Palace by a covered fortified corridor.- 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.