This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

Monasteries on rock pillars, once accessible only by frayed ropes.

Come for the flowers, stay for the bats!

This historic observatory contains the world's oldest refracting lens telescope.

France's most famous cemetery, with some of its most curious tombs.