This "preacher's pulpit" once used for pagan ritual, is home to a new, and dangerous ritual.

Walk 2,300 feet above the ground on the "Troll's Tongue."

The now-overgrown beach resort was once frequented by Yugoslav military elite.

One of the world’s longest pedestrian suspension bridges.

Perhaps the most spectacular grotto along the Algarve coastline.

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

A unique seaside cave where Aleister Crowley faked his own death.

In Portugal, a secluded stretch of untouched natural beauty hides at the bottom of a steep hill.

Buildings that dynamite couldn't bring down were abandoned because of bathroom issues.

Board a mine car and descend the #190 slope 300 feet underground into the Clark Vein of coal.

It would take 35 firetrucks to fill this enormous glacial pothole.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

Gods clash with machines in a power plant regenerated as a museum.

The origins of a large, medieval castle are shrouded in mystery, but now it's a delightful garden.

According to tradition this is the oldest church in Venice, but its actual age is a mystery.

A small island less than half a mile from Venice is a forbidden island with a dark and twisted past.

An ancient fortification lives on in this Chinese city.

One of the most well-preserved castles in Italy also contains a rare medieval example of a port fortification.

This daunting 1st century fortress was purportedly the site of one of the most dramatic revolts of the Jewish-Roman wars.

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

This historic island prison holds one of the dungeons from the Count of Monte Cristo even though it is a work of fiction.

This sprawling Belgian fort was once thought of as impenetrable but now it is simply an abandoned relic.

This Nazi ruin was the site where Hitler was almost blown up by a suitcase bomb.

A castle-like sea fort from the 17th century is now a museum to oyster farming.