The ominously named cave is home to some remarkable ancient art.

This was once the center of the Birdman cult, and is now a World Heritage Site.

This three-chambered cave is the only protected natural bat hibernaculum in Quebec.

An abandoned town centered around a paper mill powered by a large waterfall.

The falls were named for the mistaken idea that they were the ones pictured on the Canadian $5 bill.

A remarkable geological formation resembling a forest made of stone.

Queen of the waterlilies, so big and strong it can support the weight of a human.

Hundreds of thousands of concrete bunkers crowd Albania long after the fall of Communism.

A replica of the decorated wooden pillars Viking sailors threw overboard when finding new places to establish a settlement.

Iceland's "Smoky Valley" is a beautiful river that is shrouded in a constant cover of steam clouds.

Once described as the "Eagle's Nest," this ruined ancient city rests on a remote mountaintop.

A little-known caravanserai hidden among farmhouses in the Turkish countryside.

The only residents of this abandoned housing development full of identical castles are stray cats and dogs.

Fantastic lake on the heart of a fault line.

Roman ruins top white travertine terraces formed by ancient hot springs.

This famous city eluded concrete detection until the early 2000's.

An underground network of massive stone arches and their skylit vaults support ruins of portico structures above.

This mysterious cliffside carving of an ancient Hittite deity has baffled scholars for centuries.

These ruins once flourished as the capital of the Lydian kingdom, often credited with the invention of metal coinage.

No one knows why ancient labyrinths were built on this tiny northern island.

During the Soviet era, the medieval capital of Volga Bulgaria served as a substitute for Mecca.

Site of the largest impact event to occur over land in Earth's recorded history.

A winery built on the site of a Gallo-Roman estate uses historical tools to recreate ancient vintages.

This medieval "painted village" is famous for its geometric facades.