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.'

Village situated on a narrow volcanic escarpment.

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

A landscape decorated with enormous skull sculptures.

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

One of Antoni Gaudí's least-visited works, an homage to Catalan patrimony that mixes neo-Gothic with Modernista forms.

The little church's beautifully frescoed ceiling has earned it the nickname “the Sistine Chapel of Madrid.”

The world's largest wooden structure.

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

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

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

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.

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

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

At the foot of a waterfall lies a peaceful swimming lagoon and evidence of over 60,000 years of human habitation.

One of Europe's largest supercomputers is housed inside of a disused chapel.

This amazing abuela became a diehard metal fan late in life and an icon of Madrid's '80s rock scene.

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

Wonderland replication in progress by one persistent man.

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

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

Bacteria and algae give the salty water its bubblegum hue.