Underground hospital complex constructed by slave laborers during the German occupation of the Channel Islands.

Rising from the sea like a stone monster.

Gouged in the mountain to make stage coach access easier through the Fremont Pass.

Granite rocks that concentrate waves into powerful jets.

Turnip-shaped island just off the Michigan shore in Lake Huron.

65 million-year-old chalk outcroppings mark the end of the Jurassic Coast.

Between Neo-Pagans and Neo-Nazis, these strange rock formations have a curious cult following and a very strange history.

Hill-like structures formed by glaciers and sandy spits of land.

Little island known for its massive beachfront "flowerpot" pillars.

Amelia Earhart's possible place of death.

This strange geological landscape erupts with sudden bursts of water.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

Windblown rock formations in an ancient Roman quarry.

Stalactites and stalagmites in a beautifully lit cave.

A geological bull's-eye visible from outer space.