A former French military respite turned jungle tourism hotspot.

The prototype for all Nazi concentration camps.

An abandoned NSA listening post on Berlin's "Devil's Mountain."

Preserved Inca city and site of the last Inca stronghold against the Spanish conquistadors.

This legendary city has been a tourist attraction for centuries.

A plaque marks the site directly below the mid-air detonation of the atomic bomb over Hiroshima.

Ancient paintings known as the "Sistine Chapel of Cave Art."

The world's largest military aircraft cemetery.

This famous city eluded concrete detection until the early 2000's.

An ancient city exhumed from the depths of the ocean.

An Italian hillside ghost town.

The palace of the King of Kings, burned by Alexander the Great.

This ghost town in Belgium will lose its street art when it ceases to exist.

The rusting remains of the largest assembled WWII fleet on the West Coast.

The final resting place of a space program monolith.

The "3rd largest" city in California is an empty mirage of suburbia in the middle of nowhere.

Once connected to the outside world by a single train track, this ghost town is looked after by the National Park Service.

America's only nuclear missile silo open to the public.

Twice a year, visitors can tour the desolate site that birthed the Atomic Age.

This French ghost town from World War II has been left as a memorial to German atrocities during World War II.

The hallucinogenic center of the ancient world.

A reproduction of earth's many biomes.

Pompeii's less famous neighbor is still revealing her secrets.

In the middle of an extremely unforgiving and desolate high desert is the most secret military facility in the world.