Bridge that died in war and was resurected.

There's a mini version of Iguazu Falls hidden in the Balkans, and it's got a rope swing.

Landscape of bizarrely shaped desert mountains and innumerable rock carvings.

Mirrors and glass shards cover every inch of this arrestingly beautiful mosque.

A subterranean Holocaust refuge within one of the world's longest cave systems.

Submerged busts of communist and socialist figures from the USSR.

In the land of the Light Brigade stands a testament to the Cold War.

A castle perched precariously over the Crimean Sea.

World's largest cave was only discovered in 1991, and now offers tours to the public.

This peculiar lake of pitch is so thick and viscous that one can walk on its surface.

Home to nearly a third of the world's mud volcanoes, Azerbaijan is home to a messy, bubbling, and sometimes explosive landscape.

Spring that emits water and fire at the same time is said to have remedial properties, and sparked its own religion.

The largest catacomb system in the world.

One of the world's largest salt caves is filled with fragile salt sculptures, salt rivers, and huge salt megadomes.

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

A shrine of fire worship built on top of a natural flame.

The second-deepest known cave on Earth, hidden in an extremely remote mountain region.

Fortified homes of highland warriors that are still in use today.