Peek into a cave of giant, glimmering crystals.

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

This small Spanish village still pays homage to the Spaghetti Western films that were shot there in the 1960s.

This abandoned, turn-of-the-century astronomy hub is now the subject of more photographs than it ever took.

The highest peak in mainland Spain is said to be the final resting place of a Muslim king.

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

A long strip of fossil-filled limestone makes up this natural bridge above a rushing stream.

This imposing modern citadel started out as a home renovation project.

The former 1920s mansion of a prominent Catalan developer was used as the Soviet Embassy during the Spanish Civil War, and there is still a bunker below the garden.

This futuristic observatory at the top of the Pyrénées offers unrivaled views.

A series of recreated fortifications mark George Orwell's path through the Spanish Civil War.

Abandoned Nazi train station turned underground astroparticle laboratory.

An arresting arch punched straight through a mountain provides one of the most scenic spots, and challenging climbs, on the planet.

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