The abandoned ruins of a beautiful medieval castle just outside Barcelona.

Stunning Roman aqueduct used for 1900 years and still standing.

Possibly the oldest church in Barcelona, this basilica has its pagan and Christian mythologies all mixed up.

The only urban monument in the world designed by the great surrealist painter Salvador Dalí.

The final resting place of the great navigator, or maybe his brother.

This house's itty bitty size means no humans allowed.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

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

This Funeral Hearse Museum represents the finest in cadaver transportation.

Giant eggs, walls of bread, and nightmare surreality mark the largest collection of works by Salvador Dalí.

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

A whimsical brother of the nearby Fallen Angel statue takes the falling part quite literally.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

Natural stone arches form a walkable "cathedral" at low tide, then disappear entirely when the water returns.

A temple to modernity, tucked away amid Barcelona's more well known museums.

Turntable anonymously received orphans, alms, and groceries.

The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

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

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

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

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

Mountain where Jesus was first tempted by the Devil.

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

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.