This four-story steel sphere in Maryland was used to test biological weapons.

Hidden in the forest are the crumbling, graffiti-covered remains of the factory where most of Germany's explosives were produced during World War II.

A long spiraling walkway winds through the woods, and around a copper beech tree at the center.

An elevator into the Baltic Sea.

The NASA scientists behind Apollo 11 started out developing Nazi weapons at this abandoned German rocket factory.

These abandoned huts still hold the remains of an early 20th century Australian researcher's work.

One of America's oldest Antarctic research bases is abandoned but still just waiting for visiting explorers.

This abandoned Antarctic base sits nearly unchanged since it was forsaken in the 1950s, just waiting for you to visit.

One of the world's southernmost bars.

Natural time capsule containing an alien ecosystem.

A cooled lava flow from the Haleakalā volcano formed these surreal-looking columnar basalt structures.

The birthplace of the very first human resident born in Antarctica.

Russian Orthodox church built on an Antarctic island.

One of only two civilian settlements in the desolate lands of chilly Antarctica.

An abandoned whaling station on an active volcano offers hot springs in Antarctica, surrounded by ruined giants of industry.

A chilly monument dedicated to the French explorer, Jean-Baptiste Charcot.

Cold storage for agricultural biodiversity.

The best place to send your postcards home from Antarctica.

Nimrod Polar Expedition base, and home to hundred-year-old frozen whisky.

Southern Ocean waters and glacial forces transform the Antarctic ice into these stunning bridges and caves.

Considered the most remote point in the entire world.

This small monument marks the divide between the Atlantic and Indian Oceans at the southernmost tip of Africa.

A monument in the Belarusian city of Polotsk claims to mark the exact midpoint of the European continent.

An unusual "skull with ears" sits in the crypt of this small church tucked away at the end of a narrow alley.