Natural mummies hidden in the crypt of a medieval French church.

This French anatomy museum greets guests with a skinless man, mid-shovel.

Two towns are linked by an engineering marvel masquerading as a boring suspension bridge.

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

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

A medieval church with largest and oldest collection of Renaissance frescoes in France.

A site where “the ravages of the war are more striking…than any other place in contemporary Spain.”

This religious complex carved into a cliff is steeped in legends of miraculous stags and the Holy Grail.

Abandoned Nazi train station turned underground astroparticle laboratory.

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

Stunning Roman aqueduct used for 1900 years and still standing.

Super Robot anime statue guards a forgotten suburban development in Tarragona.

Abandoned waterpark turned counter-culture mecca.

A Spanish forest is filled with mysterious stone carvings.

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

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

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

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.

A once-secret library of Freemason history in Catalonia.

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

The studio of Catalonia's most famous theatrical designer remains exactly as he left it.