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

This historic stone bridge has an entire neighborhood clinging to its sides.

A restaurant and observation deck built in a unique broadcasting antenna.

Berlin's old airport.

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

The most visited, and possibly most controversial, museum in Germany.

The largest ice cave in the world is thought to be the entrance to hell according to Austrian legend.

This historic Chinese tower was said to have been haunted by fox spirits but is now haunted by a grisly murder.

A decaying, yet still functioning, work of communist architecture.

This fifth-century church is one of the oldest Christian sites in the Balkans.

This massive concrete sculpture is said to be the heaviest communist monument on Earth.

Hundreds of thousands of concrete bunkers crowd Albania long after the fall of Communism.

This ominous Albanian fortress houses tanks and downed planes as a reminder of their victories over Western imperialism.

A medieval bridge stretches over a sulfur-rich river that leads to year-round natural hot springs.

St. John the Baptist's forearm is housed in this remote 11th-century monastery.

These abundant, over-the-top monuments are so widely scattered that they define the entire compact capital cityscape, often leading to jokes about whether there are more statues than residents.

Depending on the region's rainfall, this church may be partially submerged.

This fortress dates back to the 6th century and is also the site of a controversial abandoned restoration project.

It's unclear what caused the fire that led to this opulent hotel's demise.

With over 10,000 lights, this engineering marvel lights up the city after dark.

A cluster of historic bathhouses built on the famed hot springs that gave the Georgian capital its name.

An old spa town in the mountains of Romania where, according to legend, the great hero Hercules once bathed.

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

The European towns of Brașov and Râșnov each have proud signs reminiscent of the Hollywood sign.