A fairytale Gothic castle steeped in Nazi treasure conspiracy theories.

The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

An underground city of salt.

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

This luxury hotel suite is located deep in the bowels of an old mine.

One of the largest legal spray spots in Hamburg.

More than 200 eclectic sculptures surround the artist's home.

This fantastical icy castle is built anew every winter.

If you visit Santa's village, you can get your passport stamped to show you crossed into the Arctic Circle.

A little-known sculpture park of contemporary environmental art in a Lapland forest.

Roughly 17 million letters to Santa have found their way to this Arctic Circle post office.

Walking through this narrow gorge will make you feel like you've fallen into a fairytale landscape.

The lost American era of gunfighters, bandits, Indians and steam trains is recreated in Sweden.

This castle ruin in the middle of nowhere is a gem for wildlife enthusiasts.

This fantastic cave remained unexplored until 1948 when three schoolboys discovered a hidden entrance.

One man's fascination with Turkey led to this backyard mini-city.

This pyramid in southern Sweden houses the remains of an eccentric nobleman, who spent his life doing whatever he felt like doing.

In the town of Åtvidaberg, the midday sun sets off a loud cannon boom.

An eclectic sculpture park rises atop a giant pile of ashes in Sweden.

Enigmatic bug-like sculptures mystify drivers along a Swedish highway.

Hundreds of mossy stones engraved with bits of philosophy, literature and random musings.

A golden egg-shaped sauna in the Arctic tundra.

The remains of Alfred Nobel's first nitroglycerine factory can still be found on the shores of a Swedish bay.

Micro-nation based around a nine-story high illegally built tower.