This massive concrete sculpture is said to be the heaviest communist monument on Earth.

An abandoned saucer-shaped monument in the Bulgarian mountains.

The last planned Soviet city was built for the former residents of Pripyat after the Chernobyl disaster.

This attraction was abandoned after the Chernobyl disaster.

One of the most poignant ruins of the Chernobyl nuclear disaster, the local football team's stadium has been quickly reclaimed by nature.

The deepest hole drilled in the name of science, where evidence of Precambrian life was found.

This derelict superstructure was a very important warning system for the Soviet military.

A fiery crater has been burning in the Karakum Desert since 1971.

At 705 feet high, Brazil's "House of Stone" is the largest cave mouth in the world.

This high-speed test track is popular with car manufacturers, speed freaks and orbiting astronauts.

These pools have been abandoned for over 20 years.

This overgrown mountain village has been abandoned for nearly a century.