Subterranean Sites

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.

Stuck in a bygone era, the oldest subterranean shopping street in Japan hides beneath the popular Asakusa district of Tokyo.

The largest underground pedestrian tunnel system in the U.S. mostly caters to the people working in the offices above, but provides a great, air-conditioned way to traverse the city.

Once one of the most polluted caves in America, now an environmental success story and a museum dedicated to caves.

This 300-foot-long underground tunnel was once used to transport food from the kitchen into the main building.

Underground attraction offering tours of the foundational ruins of a church nave that collapsed in 1674.

The warmest cave in the Ozarks features two seemingly bottomless lakes.