Once thought to be the mysterious work of a witchy prophetess, a well with unusual properties turns objects into "stone".

A former French military respite turned jungle tourism hotspot.

The rust covering this old mine's abandoned buildings matches the red pigment it once produced.

Largest necropolis in the Mediterranean.

What looks like a suicide in progress is actually a statue of Sigmund Freud.

The first museum in the world devoted to sexual gadgetry.

The hidden lair of an alchemist rediscovered in a 2002 flood.

Fantastically decorated underground chambers built in the 1760s.

This crumbling folly looks like an enchanted left over from Middle Earth.

Crawling into this primordial cave may feel disconcertingly familiar.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

Located in the thermoelectric factory that once powered the entire city, this Portuguese museum is shockingly fascinating.

Vietnam's feral abandoned water park offers access to a post-apocalyptic funscape, now with fewer crocodiles.

This Vietnamese hell cave lets visitors take a walk through a devilish underworld full of demons.

Medical history with an amazing, if frighting, collection of wax diseases on display.

A geological oddity topped with a 2,000-year-old pagan temple.

A cave dwelling that was started by the Celts, expanded by monks, and finished by knights.

The mystery of the Putim Ossuary involves a tricorn hat.

The ceiling of Prohodna Cave in northern Bulgaria affords a peek at the sky via two deity-sized-eye-shaped holes.

A tiny microvalley etched into the side of Knocknarea Mountain hides another world.

An Escher-inspired library dedicated to the wonders of the human mind, yet closed to the public.

A small Portuguese cottage formed between boulders in the countryside.

This Scottish bridge seems to compel dogs to leap to their death.

Beasts and branches swirl in sandstone carvings, interrupted by one strange creature.