An abandoned concrete jungle surrounded by a lush park.

The "World's Largest Underground Business Complex," a 55,000,000-square-foot city underneath Missouri.

A unique collection of Soviet military artifacts lies hidden away in a disused train, in the unrecognized Eastern European republic of Transnistria.

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 ghost town left by the worst nuclear disaster of all time is being taken over by nature and urban explorers.

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

Padlocks cover this rickety footbridge with love.

A forgotten remnant of the Soviet Union, Transnistria is an unrecognized country hidden behind a heavily militarized border between Moldova and Ukraine.

This sign marks the entrance to a tiny proto-state within the small country of Moldova.

The largest wine cellar in the world is a 150-mile network of underground caves near the capital of Moldova.