Dating back almost 400 years, the oldest public collection library in the United Kingdom was once the study hall of Karl Marx.

This beautiful Victorian ironwork masterpiece was built to keep London from smelling like poop.

England's most notorious suicide spot.

Artists and musicians now rule over this former rail station.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

A historic London pub with prison cells in the cellar and a "spy room" on the second floor.

Wedged between two buildings at the Great Ormond Street Hospital is this secret music installation.

A student driver's nightmare.

A tongue-in-cheek arcade where the games are based on everyday life.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

A kaleidoscopic warehouse-maze of handmade neon signs.

Browse through roughly 130,000 titles in the world's largest independent video rental store.

Rifle through images of skyscrapers, Worlds Fairs, and more in the largest public postcard repository in America.

This deceivingly ordinary warehouse hides an enormous collection of pop culture treasures.

An artsy hidden staircase leads to breathtaking views of San Francisco.

Radical Bookstore and Community Space.

Dim sum, served in a grand old theater.

The oldest Italian café in Boston, this spot also serves as a veritable museum of vintage coffee ephemera.

This upscale streetwear store is hidden behind a fake Snapple machine in the back of a deli.

The bookstore with bookshelves built into unlikely places.

The crypts are so large they're basically their own underground church.

An abandoned water sports stadium that has become a haven for graffiti and decay.

Breathtakingly blue walls shimmer inside the "Glacier Behind the Town."