The beautiful baroque library of the Hapsburg empire.

Ruins of a German Castle on top of a towering stone pillar.

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

An eerie, derelict amusement park in Berlin.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

The fairy tale castle of the "fairy-tale king."

An abandoned NSA listening post on Berlin's "Devil's Mountain."

Rusting away on the edge of New Jersey are the remains of a Cold War missile launch site.

This "floating railway" is one of the world's oldest monorail systems.

Less a museum than a bizarre fantasy world created by artists and engineers.

Abandoned railway line circling the city of Paris.

Colorful and chaotic stacked hotel in North Holland.

A beautifully eclectic mix of architectural styles.

This 1920s Amsterdam neighborhood was built as a giant experiment in concrete construction.

They squeal, they nosh, they look like predators.

Experience park where visitors are told to expect the unexpected.

Abandoned waterpark turned counter-culture mecca.

A gravity-defying "devil's bridge" that has a surprising architectural feature for its stability.

Cursed swimming pool left abandoned is now a favorite of filmmakers and ghost hunters.

A beautiful but toxic fountain of mercury.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

The atmospheric road was never meant to be so creepy.

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

Empty, but not abandoned, this cavernous Brooklyn loading dock was once considered the largest individual building in the world.