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

Abandoned Nazi train station turned underground astroparticle laboratory.

A blunder resulted in these charming stone-lined streams becoming the target of a Nazi bombing.

A museum in south England celebrates the amphibious vehicles that cruise on a cushion of air.

Submerged ruins of a Neolithic coastal settlement, where houses, wells, graves and skeletons have been unearthed.

The Cambridge pub where Francis Crick announced that he and James Watson had discovered the DNA double-helix.

Numberless clock creates a meal of time for the dreaded, insectile Chronophage.

Men in rubber-soled boots serve as your "brakes" on this toboggan ride Hemingway described as "exhilarating."

A petite castle folly in the English countryside.

The oldest known university in the world is in Fez, Morocco.

You can cross from one country to another in a single hop on this little bridge.

"The Donut" was built as part of an expensive, ill-fated engineering endeavor.

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.

Chicago’s incendiary role in the labor movement.

A Nazi concentration camp and Anne Frank's place of death.

A preserved college lock-up that recalls a clubhouse approach to discipline.

The broken skateboards that became a poignant memorial to a murdered skater.

A black and white painted wall creates an optical illusion in the California desert.

The construction of a tram line unveiled hidden remnants of the old medieval city.

Remnants of cells from the most notorious London prison may lie in the basement of a rare Victorian Gin Palace.

These century-old beehive-shaped kilns were built to produce charcoal for nearby mines.

Stroll through Welsh history in a village of reconstructed structures.

These 40,000-year-old stenciled hands are older than the famous cave art in France and Spain.

The last inhabitants of one of the U.K.'s most remote islands were evacuated in 1930.