One of Ireland's most infamous prisons for rebels including men, women and children.

Legend says lovers who hold hands while venturing along this stone jetty and kiss at the end will remain together forever.

This ancient Irish tower could easily have stood in for Rapunzel's prison.

The remains of a small medieval chapel mark the legendary birthplace of the patron saint of Wales.

A wildlife paradise, this island is one of the world’s most important habitats for burrow nesting seabirds.

This ghost town in Belgium will lose its street art when it ceases to exist.

The last bastion of Roman presence north of the Alps looms over a German town.

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

An exact replica of a colossal Olmec head sits atop a pyramid within a Madrid traffic circle.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

Fortune tellers, snake charmers, poets, and storytellers all gather on this historic square in Morocco.

An Ethiopian "Jerusalem" featuring a church hewn out of a single rock.

The hottest place on the planet.

Reaching the "Church in the Sky" requires scaling the cliff face of a sandstone pinnacle with a 650-foot drop.

Ethiopia's "smoking mountain" is in one of the hottest regions on the planet and is home to two lava lakes.

This communist behemoth is the heaviest building in the world and a legacy of a brutal regime.

This massive underground salt mine now holds a sci-fi theme park in its depths.

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

This artificial ring island was built to hold cubic tons of polluted dirt.

A late-medieval Dutch castle with trick fountains in its whimsical water gardens.

The tallest waterfall in the Netherlands is a lovely, stepped feature that is only 50 feet tall.