Rocamadour, France is built on a rock in the middle of the Causse de Gramat. This is a vast slate plateau and part of the Causse du Quercy. The city is the most visited pilgrimage site after Lourdes in France.
Explore the ancient caves of Hang Son Doong, Vietnam. Hang Son Doong is one of the largest caves in the world and features a fast-flowing underground river. For spelunkers, exploring Hang Son Doong is the equivalent of scaling Mount Everest.