A VT member wrote the following comment about visiting Rome:
Castel Sant'Angelo by Sarita76
Castel Sant'Angelo was built by the Emperor Hadrian (117-138) as a Mausoleum. It became a fortress with the Emperor Aurelian. In 1277 the Pope Nicholas II connected the Castle to the Vatican through the famous corridor. So the Popes used it as a fortress and as a prison and a place for torture.