A Black Forest cuckoo clock theme park features one timepiece big enough to walk inside.

The birthplace of Karl Marx is now a museum dedicated to the communist revolutionary's life and work.

Its town washed away centuries ago, this lonely tower by the sea tells the tale of a mermaid and a curse.

One of the world's few mounted blue whales, its jaws are hinged open allowing visitors to descend into a lounge.

Model Trains and Much More in Hamburg.

A sinuous path among steep cliffs creates a stunning sight in southwestern Serbia.

A 19th-century subterranean reservoir repurposed as a contemporary art cave.

A subterranean playground in an abandoned slate mine.

This chain of artificial lakes was an ideal test ground for the aircraft that would carry the "bouncing bombs" used by the WWII "Dambusters" squad.

A boulder carved into the shape of the cosmonaut's head.

Old Danish castle immortalized in Shakespeare's Hamlet.

This chimerical bridge/tunnel appears to dead end right into the sea.

This ultra-modern wooden boardwalk turns the ocean into a swimming pool.

The largest bottled beer collection in the world holds over 22,000 unique beer bottles.

Pre-Nazi swastikas adorn the sculpted pachyderms flanking this brewhouse portal.

Once the tallest building in the world, this abandoned church is now a monument to the destruction of WWII.

Underneath a chalk hill in France lies what Hitler hoped would be the underground launching base for a devastating new weapon.

If they push on just the right spot, even the weakest person can move this titanic boulder.

There are plenty of wonderful panoramic vistas in Edinburgh, but not many are hidden smack in the middle of the Old Town.

Remnants of an exploded schooner and wrecked submarines form a breakwater.

Hidden just under the waters around this Turkish island are the ruins of a once great city.

A factory director designed what was the world's longest suspension footbridge in 1923 so his employees could get to work safely.

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

These blingy, baubled skeletons lie in glass boxes inside a baroque Bavarian church.