An abandoned football stadium with a tragic past.

The site of one of the largest prison escapes of World War II.

Dubbed "Wistom" by locals, this abandoned factory is an urban explorer's dream.

One of the largest amphitheaters in Europe is a former Nazi gathering place that still stands today.

In northeastern Poland, the ruins of a massive granary overlook the Narew River.

A World War II torpedo launch station abandoned off the Polish coast.

A haunting deserted hotel is a favorite with artists and photographers.

An abandoned Nazi explosives plant founded by the inventor of dynamite is now an underground museum.

What was once an underground Nazi city is now Europe's largest bat reserve.

An abandoned Jewish sanatorium is tucked within the woods of Poland.

A 90-ton, gravity-defiant steam locomotive shoots for the skies in this bizarrely beautiful public artwork.

A mysterious structure left behind on the Polish mountainside, sometimes called "Hitler's Stonehenge".

A menacing statue of this mythical creature can be seen at the legendary site of the monster's lair.

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

The site of the first battle of World War II.

Warsaw's fantastically preserved gasworks...almost.

This Nazi ruin was the site where Hitler was almost blown up by a suitcase bomb.

An underground city of salt.

Amsterdam's Red Light District leaves little to the imagination.

This museum explores the tumultuous history of Lviv under Nazi and Soviet occupation.

The largest park in Lviv is surrounded by a network of disused rail tracks.

Monumental sculptures guard many of the graves, transforming this necropolis into an open-air fine art museum.

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

Ukraine's oldest operating pharmacy now offers guests a fascinating walk through apothecary history.