This huge abandoned fortress hidden inside a mountain holds a world of subterranean secrets.

These magnificently sculpted tombs represent Spain's own legendary version of "Romeo and Juliet."

This multi-level, aqueduct-footbridge hybrid is one of the greatest works of the Spanish Renaissance.

Translating as "The Jump of the Girlfriend," this stunning waterfall has a tragic legend behind it.

A large collection of steam engines, organs, and fairground attractions.

This captivating Bronze Age timber circle spent centuries concealed by the tides.

This skewed English house has looked like it's going to fall over for centuries.

Cliffs full of fossils at the portal to England's Jurassic Coast.

This Roman quarry once held secret masses and smuggler's contraband and is now home to rare species of bats.

Rare and strange weather predictors, from mercury barometers to leech prognosticators.

This restaurant's specialty is "a major enigma for food historians."

Don't be fooled by this fake medieval facade even if it is almost 300 years old.

This dramatic landscape hidden on the Isle of Skye looks as though you've stepped into the magical realm.

Ancient cliffs resembling a kilt on Scotland's second largest island emit an entrancing sound.

On this stunning Scottish island, you can walk in the footsteps of dinosaurs.

This beach runway is off limits during high tide.

During this Shetland Islands celebration, hundreds of torch-carrying "guizers" lead a procession to burn a viking longboat.

A comfortable-looking armchair and a grandfather clock have been sitting on this sidewalk for the last 30 years.

Elaborate tile work in this railway station tells the story of Portugal.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

The corpse bride of Portugal.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.