The remains of this deep, dark mine have left behind a haunting rocky warren of tunnels.

This modern labyrinth lies in the shadow of a ruined medieval castle.

Now in ruins, this castle stood for centuries and saw a number of gruesome events.

A meandering boardwalk across the bogland leads to a "stairway to heaven" with sublime views.

A square stone tomb marks the spot where six men were killed while holding a service in Caldoris Wood.

A historic cave in Scotland once served as a hiding place for a famous Covenanter.

Near this coastal cave stands a small memorial to the hermit who made it his home for three decades.

Legend says this cave housed a 16th-century cannibal and his family of 48.

A cross marks the spot in a small Scottish village that claims to be the exact center of the country.

A glacial pothole was once a hideout for a notorious Scottish outlaw.

More than a century old, this cast iron bridge on the Balmoral Estate leads to nowhere.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

A Romanian church built from one single oak.

These natural stone bridges are the largest on the European continent.

A Roman monument to their own civil engineering prowess.

Romania's "Red Ravine" is a little-known natural wonder that bears a resemblance to the Grand Canyon.

Climbing to the top of the cathedral's bell tower offers sweeping views of these medieval ruins.

No one knows who built this strange cave of worship or exactly why.

Gigantic Romanian salt mines used to heal respiratory conditions.

A giant portrait of an ancient king looms over the river.

The hallucinogenic center of the ancient world.

A medieval bridge stretches over a sulfur-rich river that leads to year-round natural hot springs.

Local lore says two enemy dragons live within these breathtaking mountain lakes.

This 13th-century monastery chiseled into the side of a mountain is equipped with a bridge that can be lifted to protect against raids.