The 1936 Summer Olympics site is a crumbling remnant of sportsmanship and a history its host country would like to forget.

"The most colorful grottoes of the world.

An intricate and amazing house built by architect Karl Junker.

A striking 12th-century-style castle built on the edge of a cliff.

An eerie, derelict amusement park in Berlin.

These Bullet-scarred bunkers are haunting reminders of the Spanish Civil War.

The abandoned club hides in the hills of Ibiza.

Disturbing winged beings decorate the walls of this strange abandoned hermitage.

Salaguti's live-in museum: a fortress against criticism and consumer art.

A house covered entirely with shells.

The atmospheric ruins of a historic church can be found on a hill above the city of Oviedo.

These magnificently sculpted tombs represent Spain's own legendary version of "Romeo and Juliet."

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

This chest hospital with a dark, haunted past serves as a fitting set for horror films and a paradise for ghost hunters.

This giant radio telescope would be a rusting ruin if it hadn't become such a beloved relic.

This colorfully-painted tunnel links two distinct parts of a historic neighborhood.

This stately council chamber hasn't changed since 1545.

This medieval castle was painted pink as part of a now-abandoned children's theme park.

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

A bizarre form of natural mummification was discovered in the church of this Frisian village.

A charming Spanish village sits atop this natural limestone overpass.

Abandoned Nazi train station turned underground astroparticle laboratory.

This miniature take on the Kremlin is one Dutch man's retirement project.

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