Khmer Rouge's high security prison.

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.

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

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

The soulless eyes of 82 bronze children stare on forever in remembrance of a horrifying World War II massacre.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

Boats must transform into railroad cars to navigate this Polish canal.

An underground city of salt.

The unsettling remnants of a torn down movie set lies nearby the ruined location of the actual Płaszów Labor Camp.

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

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

Ruins of a late 1950s Polish ski jump ramp in the middle of the city.

A Nazi concentration camp and Anne Frank's place of death.

A 12th-century fortress containing some of Berlin's oldest buildings.

The birthplace of Karl Marx is now a museum dedicated to the communist revolutionary's life and work.

Originally envisioned by King Ludwig II to rival Versailles, Herrenchiemsee's "New Palace" remains half-gilded for lack of funds.

Cold war icon and onetime "hole" in the iron curtain.

The last bastion of Roman presence north of the Alps looms over a German town.

In this truly magical place, rent hasn't been raised since the year 1520.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

Hitler's bleak vision of relaxation still stands as a mostly abandoned 10,000-room resort complex.

Dress up like a miner and take a slide into the disco-lit depths of this once foundational salt mine.

A castle from the Holy Roman Empire that hosts traveling youth... in its stables.