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

This Luxembourg cave is covered in cryptic looking marks left by mining activity.

This noble mash-up in eastern Luxembourg is part Medieval, part Renaissance, all castle.

This tri-part waterfall is a little bit of fairytale beauty in the heart of Luxembourg's Little Switzerland.

Once the local rulers had gone these enchanting ruins housed common folk in an almost real life fairy tale.

Dedicated to the American general whose reply to a German demand for surrender was simply "Nuts!"

A dream-like maze full of strange art, surreal spaces, and fantasy landscapes to get lost in.

Mysterious rocks that ring musically when struck.

Walk in the footsteps of the gods and straddle two tectonic plates.

A bit of the Berlin Wall was gifted to the Icelandic capital to commemorate the 25th anniversary of German reunification.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

An encyclopedic collection of mammal penises.

Iceland's tribute to its thankless civil servants.

This verdant, tree-lined Reykjavik graveyard is both enchanting and eerie.

One patriotic farmer's ode to the 9/11 tragedy remains even after the farm changed hands.

In the mid-19th century, an eight-sided house was the latest fad.

Curtiss is a forgotten figure in the early history of flight.

An endless sea of white conical domes.

This amended headstone marks the grave of a participant in one of the most successful military deceptions of all time.

One of the largest fleets of armored vehicles in the world, sitting out in the California desert.

Deep in the Negev Desert, the world's tallest solar tower looks like a sight straight out of science fiction.

The Denver airport is guarded by a 32-foot-tall sculpture of a demonic horse.

Once an unstoppable source of gold and silver, this town came to a grinding stop when the groundwater proved deadly.

An actual 1957 Cadillac De Ville, encased in 15 cubic yards of concrete.