Castel Sant'Angelo

Built as a tomb for the Roman emperor Hadrian and his family, Castel Sant'Angelo, also called the Mausoleum of Hadrian (Mausoleo di Adriano), is a towering cylindrical rotunda that was once the tallest building in Rome. Later Roman emperors were also laid to rest here. The mausoleum dates from 139 and is credited to the architect Decriannus.

The popes later turned the building into a fortress and castle dedicated to Saint Michael the Archangel, who gives it its present name. Today it is a museum and a protected Italian national heritage site, standing in Parco Adriano and drawing more than 900,000 visitors a year. It suits visitors interested in how a single structure passed from imperial Roman tomb to papal stronghold.