Italy has lots of beautiful little medieval towns perched on a rock, but Bagnoregio is extraordinary. Founded by Etruscans on an unstable, crumbling plateau, and perched on a spectacular cliff edge encircling and slowly destroying the town by erosion and landslides, it’s only accessible now by a narrow footbridge.

It’s also the birthplace of Saint Bonaventure, so when the townspeople rebelled against their terrible rulers in 1457 and destroyed their castle they then petitioned the Pope for Papal protection and got it, to stop anyone else trying. The only invasion these days is tourists, but you have to go, too!