A strange house built only at night, with rumored mystic inspiration.

This geothermal hot spring hides beneath a slowly growing mineral dome.

One person's lost luggage is another person's treasure.

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

360° views of the city plus five floors of optical illusions and hands-on science.

Macabre astrological automaton clock dating to the late 1400s.

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

A hospital closed seemingly in the middle of operations, leaving behind fodder for horror films and ghost hunters.

A haunting collection of the vanished and disappearing natural world.

Established in 1638 to battle the Black Death, Hortus Botanicus Amsterdam is a treasure trove of rare flora.

An underwater city for the dead.

Museum preserving torture methods from the past.

Once a mortuary that held the remains of Buffalo Bill, this Denver hotspot is now a death-fixated restaurant.

These delicate buggers are some of the rarest fossils that have bubbled up from the Tar Pits.

Bigfoot prints, Feejee mermaids, and haunted dolls on display in a tiny North Carolina town.

A beautiful geyser under environmental threat.

A 30-acre garden inspired by the principles of modern physics.

The most visited, and possibly most controversial, museum in Germany.

This unique structure in suburban Austin is made up entirely of other people's castaways, and constantly changing.

Seemingly grown on some other world, these New Mexico rock formations look like a disused science fiction set.

A pair of slides and a tree-lined stair corridor have been an urban oasis for nearly 40 years.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

The most iconic structure in Scotland has been home to bishops, colonels, and Sean Connery characters.

The fountain marks the area where hundreds of accused witches were burned at the stake.