The mysterious megaliths have enchanted and intrigued visitors for thousands of years.

An ancient Egyptian temple in the middle of Madrid, Spain.

Its appearance in "Game of Thrones" may spur on the long-awaited restoration of this medieval shipyard.

A 19th-century mansion houses the largest collection of gin in the European Union.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

This former Baroque palace on the historic Calle Montcada is a rare architectural gem and was once the meeting place of an aristocratic scholarly society.

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

Volcanic rocks ground down into sand make this Spanish beach as black as night.

An architect transformed this abandoned cement factory into his castle-like workshop.

Commonly acknowledged as the only public monument to the Devil himself.

A stately palace has been converted into the world's largest cannabis museum.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

The hidden ruins of an old hydroelectric plant reclaimed by nature.