This series of Scottish caves has no clear purpose other than baffling historians.

One of the oldest cemeteries in Germany was originally used for victims of a cholera epidemic.

Berlin's old airport.

This museum is filled with an eclectic collection of unique inventions.

The ruins of a medieval castle that once belonged to one of the most powerful families in the Netherlands.

An old asylum graveyard that's been abandoned for half a century attracts those seeking a dark thrill.

Walk through Czech history in Prague's largest graveyard.

The history of occult science is turned into a creepshow at this lurid Prague tourist attraction.

When German-Iraqi relations broke down, this embassy was vacated post haste.

Gardens representing parts of Asia, Europe, and the Mid East are tucked away among the Soviet-style buildings in East Berlin.

Berlin's natural history museum houses the world's largest mounted dinosaur and the late beloved polar bear Knut.

A narrow passage next to a cafe leads to a courtyard exploding with murals, tags, and paste-ups.

Started as a kitchen garden, now the second largest botanical garden in the world.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

An eerie, derelict amusement park in Berlin.

This medieval castle was painted pink as part of a now-abandoned children's theme park.

An overgrown and largely forgotten cemetery lies hidden within the outskirts of Amsterdam.

Pull up and have a drink at a museum filled with hundreds of years worth of shipwreck artifacts.

A true Valhalla for cactus and succulent lovers.

This miniature take on the Kremlin is one Dutch man's retirement project.

A miniature city, once ruled by the Queen of the Netherlands.

The ruins of this Dutch castle sit atop a labyrinth of once-secret tunnels and passageways, dating back over 900 years.

Unsurprisingly, Holland is home to one of the most magnificent flower gardens in the world.

An ancient passage filled with stalls selling used books, once frequented by Vincent Van Gogh.