Terrifying derelict military hospital once housed a recuperating Hitler.

Ruins of a German Castle on top of a towering stone pillar.

An eerie, derelict amusement park in Berlin.

This abandoned five-star hotel is now a five-star urban exploration destination.

This star-shaped military outpost is now simply trying to protect itself from neglect.

A small Portuguese cottage formed between boulders in the countryside.

Houses are tucked between, on, and underneath giant boulders.

This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

This quaint Spanish village agreed to be painted blue as a marketing stunt but found that they preferred it that way.

This ancient Spanish castle sits high upon a hilltop.

A medieval village holds a very modern hotel.

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

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

Of course Salvador Dalí lived in a castle...

A Romanesque tower appears when water levels drop.

Considered the birthplace of the Copper Age and Bronze Age, the river is tinted red from 5,000 years of mining.

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

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.

Cursed swimming pool left abandoned is now a favorite of filmmakers and ghost hunters.

Natural stone arches form a walkable "cathedral" at low tide, then disappear entirely when the water returns.

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

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

Most prolific publishing house in the 1600s open to the public.