An engineering error ensured this cavernous 350-foot-long subterranean thoroughfare was never used as intended.

This fairytale house on the shore of a Chilean Lake oozes an eclectic mix of Chilote and German Cultural heritage.

This striking steel sculpture transforms environmental data into art.

The rusting relics of Southampton's former luxurious flying boat industry.

A 19th-century funicular railway shuttles visitors up this surprising sea cliff to one of the world's largest camera obscuras.

The extensive relics of an ancient Roman and Phoenician fish processing plant hide in a town park.

Lumps of significant stone from around the world surround a flaming monument for peace.

A mysterious medieval monument said to mark the final resting place of Robin Hood’s henchman.

A display of hand-built replicas of the legendary vessels used by Patagonian and Antarctic explorers.

A working farm turned into a museum dedicated to the world's most unbelievably tiny cars.

An aeronautical-themed resort forged around rusty relics from the golden age of air travel.

These tenacious 14th-century towers defied demolition and are now a fairytale vacation rental.

A striking 500-year-old mansion provides an unexpectedly sublime home for live deer and a menagerie of exotic stuffed animals.

A 246-foot-high revolving restaurant rises unexpectedly from a forested Finnish hilltop.

Hidden in a grotto 26 feet below Nottingham's oldest hotel, this stylish subterranean drinking den is notoriously hard to find.

Dedicated to the first German Chancellor, Otto von Bismarck, this aging edifice is the only one of its kind in the Americas.

A 600-year-old mini shrine guarded by a sword-wielding knight hides in a crumbling cliff face.

These bleak 800-year-old ruins were once the royal residence of choice for hunting in Sherwood Forest.

Lord Byron's embalmed body lies within this medieval church.

A magnificent mansion hides a delightful collection of historic timepieces.

A sliver of 19th-century Germany sits on the shore of a Chilean lake.

There's a labyrinth of medieval chambers hidden deep below a 15th-century pub.

This bright yellow bridge is a true engineering feat.

Legend says this little-known stone circle is formed from people petrified as punishment for dancing on the Sabbath.