Underground

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.

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.

An inverted staircase above the entrance to the Bethnal Green Underground Station functions as a memorial for people who lost their lives during the worst civilian disaster in the U.K. during World War II.

The largest Spanish artifact built in the Philippines and one of the oldest underground reservoirs in the world.

Explore the flooded remains of a limestone mine in Kentucky.

These purpose-built WWII air raid shelters, which run half a kilometer under the town of Mellieħa, are among the longest in Malta.

Inside a former smuggler's cave, an artificial waterfall and light show.

A historic cavernous cistern lies hidden behind a wall at San Marino’s stamp and coin museum.

Underneath the well-known Lindenhof hides a secret cellar documenting Zurich's early history.

This 500-year-old stepwell descends seven levels deep into the ground.

An antiquated aquarium housed in a converted government anti-nuclear bunker.

A small cave network was discovered under a home in Xagħra, in 1924 when the owner was digging a well.