Hidden well off the beaten path in Catalonia is this crumbling medieval castle that is slowly being covered in graffiti.

Abandoned waterpark turned counter-culture mecca.

This abandoned racetrack looks like it is set to hold competitions in the apocalypse.

An ornate tower shows off a local artist's architectural flair.

This ancient Spanish castle sits high upon a hilltop.

Mine shafts and hard pastries await visitors at this massive mountain of salt.

Holy Grotto of Montserrat Monastery holds one of Europe's mysterious black Madonnas.

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

These striking ruins of a castle resemble a ship's stern.

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

The quirky - and private - constructions of a secluded artist depict the house of God.

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

Religious dwelling in a Spanish volcano.

Wonderland replication in progress by one persistent man.

A Romanesque tower appears when water levels drop.

Of course Salvador Dalí lived in a castle...

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

Famed architect Antoni Gaudi built this generous thank you gift to a friendly host who housed him during a job.

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

Sanctuary on a ridge near an ancient shrine to a "Black Madonna" built by the founder of Opus Dei.

Abandoned Nazi train station turned underground astroparticle laboratory.

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

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

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