This abandoned gold mine found a second life as a post-apocalyptic film set.

This multi-level, aqueduct-footbridge hybrid is one of the greatest works of the Spanish Renaissance.

The cathedral of a controversial, conservative, schismatic sect that declared the Catholic Church heretical and founded its own succession of popes.

A New York–based physician returned home to Spain to build his own elaborate monument to Christopher Columbus.

This Arab fortress was once the largest citadel in Western Europe.

This 47-story "M" needed 20 years to be completed

A magnificent, long-abandoned castle built in the wake of the reconquest of Spain.

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

A historic Christian shrine nestled within a spectacular natural cave.

A breathtaking canyon offers stunning views and frightful pathways through an ecological paradise.

This ancient Spanish castle sits high upon a hilltop.

Abandoned Nazi train station turned underground astroparticle laboratory.

Moorish signal station on a stratgic rocky outcrop.

A charming Spanish village sits atop this natural limestone overpass.

Stunning Roman aqueduct used for 1900 years and still standing.

A Franco-era dam flooded (almost) everyone out of this centuries-old Aragonese town.

This awesome Spanish castle is so fantastical it was actually used on Game of Thrones.

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

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

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

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

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

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

Inside the Šomoška National Nature Reserve exists a unique rock formation rarely seen in the world.