A striking symbol of the Bulgarian capital.

This abandoned Soviet circus is slowly being restored to its Communist-era glory.

The dining hall that nourishes workers in Chernobyl's Exclusion Zone is also open to visitors.

One of the largest museums in Ukraine remembers the story of the German-Soviet War in iconic, brutalist style.

The deepest metro station in the world.

340-foot statue built to honour the Heroes of the Soviet Union.

A reconstructed medieval gateway that was the magnificent entrance to the capital city dating back to 1037.

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

This attraction was abandoned after the Chernobyl disaster.

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

One of the world's tallest statues is also one of its most hated.

Gargantuan home of Russian science.

Former headquarters of the KGB.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

A crumbling cathedral condemned by an earthquake.

An historic and oft-filmed spot for musclebound iron pumpers on the Pacific coast.

After starting as a whimsical tourist attraction that eventually found its way to ruin, these renovated canals offer a lush and exotic locale on the Pacific Coast.

Most-visited and most-photographed slot canyon in the American Southwest.

A monument to the one-armed geologist who led the first documented expeditions through the Grand Canyon.

The lowest point in North America is home to an undrinkable pool surrounded by fields of geometric salt flats.

This crumbling Death Valley mining complex was known for its use of giant, 20-mule team wagons.

The lighthouse central to the 1980s horror classic "The Fog" is, in fact, located in one of the foggiest areas of the Pacific Coast.

Golden Gate Park's historic collection of plants.

This private residence was the template for one of the most beloved television homes of all time.