Be careful not to get trampled at this lively two thousand-year-old market.

The world's largest natural arch was forgotten for over 50 years after its discovery.

This dark, damp, perilous tunnel is the only passage from north to south Tajikistan.

The Avenue of Mausolea is a series of grand palatial tombs.

At 72 feet below sea level, it's the lowest commercial airport in the world.

Once a bustling fishing port, this semi-ghost town is now more than 90 miles away from the shore.

Former island in the Aral Sea used to be a top-secret Russian bio-weapons facility.

Rusting ships sit in a desert where a sea used to be.

World's oldest and largest space launch facility, once a secret missile testing site.

The remains of a monument in the remote Kazakhstani desert dedicated to the only men to die in outer space, the crew of the Soyuz 11 rocket.

The world's most remote permanent settlement on an active volcano.

It might not be as impossible to reach as its name would imply, but just about.

Final resting place of Antarctic explorer Ernest Shackleton.

This abandoned Antarctic research station is a Soviet ghost frozen in time.

Australia's only active volcanoes and highest peak are located on these remote islands thousands of miles away from the mainland.

Considered the most remote point in the entire world.

Naked scientists race around the pole in the frigid cold to try to join Antarctica's exclusive 300 Club.

Largest sub-glacial lake ever discovered.

An ice field known for harboring an infamous Martian meteorite turned out to contain the oldest air on Earth.

Scientists use one of the saltiest bodies of water on Earth as a terrestrial base for studying water on Mars.

Natural time capsule containing an alien ecosystem.

One of the most extreme deserts in the world, these snow-free valleys harbor life, despite the hostile environment.

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

These giant volcano sponges in Antarctica are thought to be the world's oldest living animal, at 15,000 years old.