Originally built between 135 and 139 by the Emperor Hadrian to be his mausoleum, Castel Sant'Angelo sits next to St. Peters and the Vatican. Due to this proximity, it has had a long and storied past. In 1227, the fortress was linked to the Vatican by a corridor, which led it to be used as a hideout for Popes and others during violent times. It was also used as a prison. In his famous autobiography, Benvenuto Cellini describes his years behind these walls as prisoner and as defender of Rome during the Sack in 1527.
The bridge over the Tiber River leading to Castel Sant'Angelo, was also originally build by Hadrian in 134 but it collapsed in 1450. It was rebuilt over time using parts of the ancient bridge and sculptures designed by Bernini. From the 16th to the end of the 19th century, the small area at the end of the Ponte Sant'Angelo was the site of countless public executions, by ax or the noose before 1816, and then by guillotine. The bridge was also used to display the heads and bodies for weeks after the execution.