Huge concrete structures designed as an early warning system for Britain to detect enemy aircraft.

The remains of Crystal Palace Great Exhibition of 1851.

Charles Babbage's proto-computer, painstakingly brought to life.

This religious museum resides in a church crypt next to the founder's house.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

Shiny Brutalist box commemorates a pioneer of electricity and houses a railway transformer.

Since 1874, this macabre collection has developed into a museum devoted to Scotland Yard's mementos of dastardly deeds.

An eerie, derelict amusement park in Berlin.

Wonderland replication in progress by one persistent man.

Ancient paintings known as the "Sistine Chapel of Cave Art."

Abandoned Nazi train station turned underground astroparticle laboratory.

A beautiful and classically designed villa, with an hourly infestation of monsters.

The Sun King's military models, saved from the Louvre.

Pitié-Salpêtrière was the dumping grounds for women who received the dreaded diagnosis of "hysterical."

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.

A grassy pyramid named after a French battle.

A former plague hospital turned medical museum.

Science fiction's grandfather has a fittingly marvelous tomb.

The encased skull that is widely believed to belong to St. John the Baptist.

This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

The Rozenberg wind wall in South Holland makes for smooth sailing through the Calandbrug canal.

Peek through a transparent pyramid and drink in the mountain made of books.

A Cold War command center is hidden under an idyllic countryside.