Once a black market electronics marketplace, now an otaku shopper's paradise.

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

The eerie burnt-out remains of a prominent building where 30 protestors lost their lives.

The prolific artwork of a self-taught sculptor.

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

A beautiful but toxic fountain of mercury.

Bask in the 19th century grandeur of an eccentric Freemason millionaire's private gardens.

A gravity-defying "devil's bridge" that has a surprising architectural feature for its stability.

This chest hospital with a dark, haunted past serves as a fitting set for horror films and a paradise for ghost hunters.

An independent naturist colony amidst 1000-year-old ruins.

A whimsical garden of outsider art in the Spanish countryside.

The deserted remains of a luxury hotel turned hospital ward.

A site where “the ravages of the war are more striking…than any other place in contemporary Spain.”

Cursed swimming pool left abandoned is now a favorite of filmmakers and ghost hunters.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

Week-long block party becomes a competition for the best decorated street.

Turntable anonymously received orphans, alms, and groceries.

Mysterious Spanish catacombs of unknown origins.

A huge cathedral single-handedly constructed by one eccentric monk.

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

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

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

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