Folklore says this medieval fortress was plopped atop a portal to hell to trap the demons below.

Tall columns of volcanic basalt make up this improbable-seeming rock formation.

Europe's largest natural bridge has a 19th century royal chateau built into its side.

Created as a "model concentration camp" to hide Nazi atrocities from the international community, this former camp-ghetto now holds a museum and memorial honoring the lives lost within.

The soulless eyes of 82 bronze children stare on forever in remembrance of a horrifying World War II massacre.

This former quarry is now a picturesque gorge that hides a sunken lake.

Heralded as one of the prettiest castles in all of Czechia.

Be(w)ar(e) the moat around this historic Czech castle.

A larger-than-life statue of the German revolutionist stands proud in a small town where he never lived.

This ruined castle perched atop a rocky peak is a great place for a hike.

A spiral staircase twists to the top of this unusual Czech lookout tower.

Countless grotesque faces stare out from this eerie Prague art wall.

A Jenga-style cylindrical tower of books that appears to go on forever.

Macabre astrological automaton clock dating to the late 1400s.

A church of bones, decorated with 40,000 human skeletons.

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

A road runs through the middle of this small Austrian chapel.

On a stretch of Danish coast known as "Cold Hawaii," this fishing village has become a surfing town.

Across the Pacific in a raft, a museum dedicated to Thor Heyerdahl's now legendary expedition.

Largest Roman Catholic church in North America.

Moscow's imposing monument to the Space Age.

Former headquarters of the KGB.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

Once the tallest building in Chisinau, this unique tower is a relic of Soviet architecture.