An ancient city hidden in the heart of the Sierra Nevada mountains.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.

This house's itty bitty size means no humans allowed.

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

Cat art as far as the eye can see.

A floating cat sanctuary on an Amsterdam canal.

This natural Icelandic fissure allows divers to swim right between two volatile tectonic plates.

Europe's second largest ossuary wasn't discovered until 2001.

Underneath this small church are 15,000 bones, arranged by an obsessive academic.

The history of occult science is turned into a creepshow at this lurid Prague tourist attraction.

An Inca spa, military outpost or maybe… both?

Mystic Incan rock piles three miles above sea level.

A fascinating little museum all about the rich history of Peru’s famous plant.

Sleep in a glass pod dangling off a cliff.

One of the world's tallest waterfalls wasn't revealed to the world at large until 2006.

The mortal remains of an estimated 70,000 people lie in the basement of a monastery in Lima, Peru.

Keshwa chaca, among the last handwoven Incan bridges, crosses Apurimac Canyon in Peru.

The world's only complete colossal squid specimen is on display at the Te Papa Museum.

This strange geological landscape erupts with sudden bursts of water.

One of the world's most advanced radio observatories sprawls across the Atacama Desert.

You can swim in these highly salty, mesmerizingly blue lakes in the Atacama Desert.

What was once a unique system of urban elevators is turning into a mechanical ruin.

A sculpture of a giant hand reaches for the stars in the middle of the Atacama desert.

Mother Nature outdoes herself with this stunningly beautiful set of caves carved into marble.