This macabre masterpiece of a mural is one of Francisco Goya's "Black Paintings."

This Navarrese cave's history of witchcraft and pagan ritual is not just embraced, but recreated each year.

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

The world's largest wooden structure.

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

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

A landscape decorated with enormous skull sculptures.

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

A Spanish forest is filled with mysterious stone carvings.

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

This whimsical winery by Antoni Gaudí looks ripped from the pages of a fairytale.

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

The morbid items in this small and hidden museum are not for the weak stomached.

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

A museum dedicated to the Spanish occult in a town that was terrorized by the Inquisition.

Wonderland replication in progress by one persistent man.

An enchanting monastery in the Spanish countryside appears lifted from a fantasy tale.

Spanning the El Chorro gorge, this pathway used to be one of the most dangerous crossings in the world.

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

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

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

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

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

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