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

An unusual sand beach in the middle of a forest.

Jean Tinguely's bizarre monster sculpture is hidden deep in a forest.

A lawn full of retired spacecraft on display at one of NASA's first research labs.

A lonely memorial to the Challenger Space Shuttle, honoring the astronauts who died in 1986.

The largest underground lake in Europe.

Traversing steep Alpine slopes, this engineering marvel is one of the longest and highest funiculars in the world.

At 929 pounds and 26 feet tall, this stainless steel fork can only be used by the likes of King Kong.

Artworks by loners, prisoners and the criminally insane.

These magnificent 240-year-old machines are considered distant ancestors of the computer.

Museum of science fiction, utopias, and extraordinary journeys of the mind.

One of the world's most complex timepieces.

Constantly maintained, this organ is playing a six-century long composition by John Cage.

A Cold War command center is hidden under an idyllic countryside.

A fantastical bed and breakfast with magically unique rooms.

Sweden's first nuclear reactor, R1, can be visited 25 meters underground.

Austria's very first and only nuclear power station was completed but never used.

The atomic museum in the basement of this German castle displays long strands of replica uranium cubes.

Launch site for nuclear war against Western Europe.

This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

A swath of France so devastated by war it is still forbidden to go there.

This former limestone quarry is now a subterranean wonderland of grand stonework.

This natural French spring has been turned into a magical grotto by Roman and medieval constructions.

One of the most powerful religious centers in the Middle Ages, dubbed the founder of Western monasticism.