These official units of measurement—including chains and perches—lie hidden beneath tourists' feet in a popular London hub.

This luxury shopping lane has been protected by its own tiny police force for over a century.

Pop culture has helped to keep this iconic British building from being destroyed.

This coffee shop lies hidden beneath a historic church.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

An artistic tribute to the famous singer, just around the corner from where he was born.

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

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

A kaleidoscopic warehouse-maze of handmade neon signs.

Touching mementoes from those who didn't make it back from World War I still hang in one of New York's oldest bars.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

One of the oldest used bookstores in the U.S. has been selling antiquarian treasures since 1825.

The century-old bell and clock tower at UC Berkeley is the third-tallest in the world, and has fossils.

This subtle Berkeley paving stone actually marks off a lawless tube of air that extends into space.

A shape-shifting buy-sell-trade bookstore, born to Beatnik Era spirit.

Julia Morgan's Moorish-Gothic labyrinth of fountains, trees, natural light and Oakland's notable dead.

A room in New York City that contains 250 cubic yards of dirt worth a million dollars.

The oldest stone house in Paris was built by its most famous alchemist.

The bar where "The Great Train Robbery" was planned was once a nexus of high society and low morals.

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

A miniature Italianate fantasy village on the coast of Wales and the set of ITC classic "The Prisoner."

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

The inspiration for H.P. Lovecraft's horror stories and Batman's Arkham Asylum is now a condominium complex.

The bronze uniforms commemorate the vital role of women during World War II.