Naturally formed rock city in Poland.

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

An underground city of salt.

The oldest badlands in North America, Makoshika State Park takes it name from the Lakota words for broken land.

The largest medical and anatomical collection in France lies hidden from the public.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

A haunting collection of the vanished and disappearing natural world.

One of the oldest medical collections in Europe focusing on rare surgical instruments.

Mysterious painted skulls in Moravia.

Mummified monks and the accidentally interred, in a 17th-century crypt.

Artfully arranged bones of 5,800 Austrians.

This small chapel is built of human bones and decorated with a golden skeleton.

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

Considered the birthplace of the Copper Age and Bronze Age, the river is tinted red from 5,000 years of mining.

Bold black and white motifs of life and death add a dramatic flair to this 17th-century crypt.

Spanning the El Chorro gorge, this pathway used to be one of the most dangerous crossings in the world.

Moorish signal station on a stratgic rocky outcrop.

A Spanish town built into the cliffs.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

The fastest mail service in the west is tracked and memorialized along this 1,400 mile trail.

See massive fossils that are over 200 million years old in northeastern Arizona.

This cave holds a surprisingly colorful variety of geological oddities.

Collection of skeletal systems from the "world's leading supplier of osteological specimens."

Nestled near the mountains of western Canada resides this behemoth earth mover.