Passetto di Borgo (Papal Escape Corridor)

An elevated fortified corridor — 800 metres long — connecting the Vatican Palace to Castel Sant'Angelo, built into the top of the ancient Leonine Walls constructed by Pope Leo IV in 847 AD. Used as an emergency escape route for popes under attack, most famously by Pope Clement VII in 1527 during the catastrophic Sack of Rome by the mutinous troops of Emperor Charles V — Clement reportedly fled along the Passetto in his papal robes, with soldiers taking potshots at him as he ran, while Rome burned below. The corridor can be walked on guided tours that include a section along the top of the walls with excellent views over the Vatican and the Borgo neighbourhood. One of the most historically charged single walkways in Europe.