This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

A unique seaside cave where Aleister Crowley faked his own death.

A micro-communist utopia in Spain with no police, no mortgages and full employment.

A stately palace has been converted into the world's largest cannabis museum.

This house's itty bitty size means no humans allowed.

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

A landscape decorated with enormous skull sculptures.

Mysterious Spanish catacombs of unknown origins.

A Spanish forest is filled with mysterious stone carvings.

Cliffside houses provide a spectacular view from their perch above the valley.

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

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

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

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

An isolated village literally built into the crevices and rock formations of a mountain.

Wonderland replication in progress by one persistent man.

This cemetery features modernist statues as strange as its name.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

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

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

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

The Cathedral of Salamanca has a number of unusual carvings but none so surprising as a modern astronaut.

One of the largest ossuaries in Spain is packed from floor to ceiling with bones.