Subterranean

This eccentric cave dwelling is bizarre even by the standards of a subterranean town.

One of the most remarkable caves in all of Iceland was created by a once raging river of lava.

This submersible road connecting a French island to the mainland is lined with safety towers for when the tide strands travelers.

A museum dedicated to a secret military hospital hidden beneath a castle in Budapest.

Decommissioned NYC subway cars are dumped into the ocean to create this underwater wildlife habitat.

An underground city of ancient quarry tunnels hid thousands of Allied soldiers in WWI.

Museum design and public transportation meet in this unique Russian train car.

A former copper mine which became a truly unsuccessful prison.

Semi-precious Blue John stones have been mined in this cavern system for centuries.

This massive subterranean fissure is known as the "underground Grand Canyon."

Behind this beachfront shop lies a spectacular, colorful sea cave with an equally colorful past.

One of the largest underground systems runs under Canada's largest urban center.

This underground power plant looks more like a super-villian's lair than a public work.

A subterranean house of worship carved right out of the bedrock.

The deepest metro station in the world.