Repurposed space and ultra-modern construction collide to create this geometric wooden spectacle.

Birthplace of the "Cat in the Cradle" and a cluster of iconic, original windmills that let the Dutch tame the seas.

A bizarre house filled with an astounding array of collections.

A palatial art deco restroom.

Made of giant chains and hung with shackles, this iron cross honors those unknowns who perished under American slavery.

Internationally recognized group that works to protect the wolf and educate the public about its plight.

This museum tucked below a charming cafe gives a brief snapshot of photographic history.

19th-century scientists would make the pilgrimage here to verify the precision of their measuring sticks.

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.

A makeshift shrine to the late rock star is still kept up on the nondescript façade outside 1 Logan Place.

The site of London's first coffee house has been serving refreshments of one kind or another for 360 years.

Catacombs turned marketplace.

The signs of a long buried road can still be found hidden beneath a London sewer grate.

Several plaster noses are hidden in plain sight around London's Soho neighborhood.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

A hands-off space for graffiti artists to hone and display their skills.

This London pub hides a peculiar secret: a recreation of the rooms shared at 221b Baker Street by Sherlock Holmes and Dr. Watson.

Hidden beneath the streets of London is a secret subway that only carried mail.

A kaleidoscopic warehouse-maze of handmade neon signs.

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

Thanks to modern navigational tools we now know that the true prime meridian runs through a park next door.

Fantastic views and thousands of love locks.

Hamburgers are intensely proud of their tunnel beneath the river.

Germany's Glienicke Bridge has a shady history of clandestine meetings, espionage, and spycraft.