Medicinal spa created with the discharge from a geothermal energy plant.

A stratovolcano located in the south of Iceland, with a long history of charted activity and a rich mythology attached.

This wrecked airplane has been sitting on a black sand beach since the 1970s.

The unique waterfall in Iceland's south features a backdrop of geometric black lava columns.

This foolish Victorian sea fort was converted to a deluxe hotel.

This remote island village was in danger of depopulating completely until a tunnel was built to connect it to the rest of the world .

The abandoned village of Skarð aptly illustrates the idiom "Don't put all your eggs in one basket."

The "Versailles of the Jungle" built by a dictator is now a decaying shadow of its hubristic grandeur.

The largest lake in the Faroe Islands seems to be held hundreds of feet above sea level thanks to an optical illusion.

A lovers' beach, tucked below the surface of the island, provides a safe haven for romance.

One of the best beaches in the entire world.

The tallest sea cliffs on the Southern Hemisphere are a climber's worst nightmare.

Walk 2,300 feet above the ground on the "Troll's Tongue."

This giant boulder is pinched over a 1000-meter abyss by two mountains.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

An underground city of salt.

Poland's oldest surviving university building holds a wealth of historic science instruments including some used by Copernicus.

This little-known relic crypt holds stolen parts of a Roman Empress.

Got apples?

The vast, legendary catacombs hold secrets much stranger than stacked bones.

This electric green sulphur lake in New Zealand looks like a cartoonish radioactive dump site.

The tallest residential building in Africa is an unsettling Brutalist monolith.

A seven-century-old jail tells a not-so-pleasant history of crime and punishment.

Pop culture has helped to keep this iconic British building from being destroyed.