Subterranean Sites

Underneath the Serapeum ruins lies a dark passage with nooks for books, the lesser-known “sister” to the famous ancient library.

Both the World War II Allied Forces and NATO have used this modern bunker underneath Malta’s capital.

This 470-meter-long dripstone cave was discovered by chance in 2006.

A remote, centuries-old underground mosque with a lunar aesthetic.

Idaho’s largest, deepest limestone cave is known for its quirky rock formations and bat population.

Mythological depictions of Laos’ national animal make this cave sacred.

A limestone cave filled with impressive formations in Mole Creek Karst National Park.

A former salt mine is now a cool picnic spot for families and asthmatics.

Erosion has transformed this sandstone boulder into a massive dune-filled cavern.

An underground spring in a labyrinthine cave system, decorated with stalagmites and stalactites.

Nature has shaped this drainage tunnel into the digestive tract of a mighty beast.

Deep in the forest of northern Denmark, this secret underground bunker was built at the height of the Cold War.

The spectacular geological formations make it one of the most impressive caves in Europe.

A network of ancient tunnels and vaulted chambers with mystical Buddhist reliefs, built for ascetic training.

Besides being home to cave paintings and pre-Columbian Cuban archaeological remains, you get to take a boat through this stalactite and stalagmite covered cave.

This impressive chasm is one of the longest natural underground cavities in the world.