Warsaw's fantastically preserved gasworks...almost.

The final resting place of more than 200,000 people, this is one of the largest cemeteries in Europe.

This open-air museum was originally a World War II testing ground for German missiles and rockets.

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

A floundering Polish shipyard was once the soul of the Solidarity movement that capsized communism.

These 18th-century paintings of Warsaw were used to reconstruct the city after World War II.

A memorial to the beloved brown bear that served in the Polish army during World War II.

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

The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

The site of the famous Nazi book burning campaign of 1933 remembers its "Night of Shame".

Golden cobblestones remember a time when this small alley was used to avoid having to give a Nazi salute.

This unique Renaissance castle was turned into a home for Nazi occultism.

Slaughterhouse Five opens its dank doors to fans of Kurt Vonnegut.

A collection of artworks exclusively created by the mentally ill that was almost burned by Nazi culture police.

This monument to those fallen in the World Wars is accompanied by a U-boat that Germany bought for a Deutsche Mark.

The site of a concentration camp where inmates were made to take part in one of the largest counterfeiting operations in history is now hauntingly empty.

A small square plaque marks a failed assassination attempt that could have changed history.

This water-tower-turned-high-end-apartment building was once the site of an early Nazi concentration camp.

An officers prison camp believed to be impregnable by the Germans saw over 30 successful escapes.

A preserved Nazi labor camp now has a Holocaust museum on site and memorials to the thousands that died while imprisoned at the camp.

A museum in the building where Nazi Germany signed its surrender tells the story of World War II from the Soviet perspective.

During World War II, the Nazis repurposed this beer cellar to store stolen artwork.

The walls of Germany's Parliament still show the scars of the Red Army takeover in World War II.

Berlin's old airport.