This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

Berlin's old airport.

Floating swimming pool within a moored vessel.

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

A fascinating insight into daily life in the Eastern Bloc.

Museum dedicated to the terror regimes of Hungary.

A Trabant car, a kangaroo statue, and a plethora of plants take over this abandoned-factory-turned-bar.

The oldest private art gallery in all of Hungary.

A museum dedicated to a secret military hospital hidden beneath a castle in Budapest.

A triumphant marble and bronze fountain depicting a 15th-century Hungarian king and his hunting party.

A museum that chronicles the history of the Nuremberg Trials for Nazi war criminals in the building where the trials were once held.

This abandoned coliseum was intended to be a grand Nazi rallying ground before it was halted at the end of the war.

This strange sculpture depicts a giant nightmare hare crushing a man to death beneath its colossal bulk.

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

One of the most easily accessible examples of the rare 1960s UFO houses.

Among the ostentatious rococo ornamentation of this church, an image of death cuts the life-thread.

Housed in an old church, this hunting museum holds a collection of mythical bird-rabbit creatures.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

People have been placing babies on these lilies for photoshoots since the Victorian era.

The location of the world's first telescope demonstration.

A modern reimagining of a medieval city gate.

These lights mark the area of Rotterdam that was bombed and burned in 1940.

Old ships and machinery fill a historic harbor in the city that's home to Europe's largest port.

Rotterdammers' dirty minds gave this santa a dirty nickname and cursed it to a life of wandering.