It is usually open only in summer in the framework of the event "Notti d'Estate a Castel Sant'Angelo".
The Passetto di Borgo, or er Corridore (the passageway), is an elevated and fortified passage that links the Vatican City with the Castel Sant'Angelo. It is approximately 800 m long, located in the rione of Borgo. It was erected in 1277 by Pope Nicholas III. On several occasions it served as an escape route for Popes in danger.