Unique antiquarian shop specializing in globes, maps, and prints.

Wine bottle sculpture with a ship's stateroom inside.

Hidden in plain sight on a pair of Manhattan subway tunnels are a pair of public instruments that sing to each other.

One of New York's best collections of pinball is hidden in a secret bar in the back of this laundromat.

A New York garbage depot holds a secret collection of weird and wonderful refuse.

Behind a bodega is a small museum of relics and ephemera showcasing the history of New York.

The "Seinfeld" diner.

Stunningly detailed mosaics in a New York subway station bring life to the Weimaraners of artist William Wegman's work—and to thousands of commutes.

The first museum in the United States dedicated entirely to posters.

The headless bodies of more than 1,300 guillotined victims of the Reign of Terror are buried here in mass graves.

Stroll through retro Paris while shopping for old postcards and discarded doll heads.

One of the few remaining examples of 19th-century London’s attempt to clean up its reputation.

The bridge is a secret gallery of discarded gum that has been transformed into miniature masterpieces.

Banksy gives themself artistic license with this piece of London street art.

A subterranean ice warehouse that has lain hidden beneath central London for over a century is now open to the public.

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

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

A network of concealed passageways lies within a busy London Underground station.

The remains of Crystal Palace Great Exhibition of 1851.

This coffee shop lies hidden beneath a historic church.

A special shop catering to the needs of things that go bump in the night, and also helps kids become writers.

The only university zoological museum in London houses extinct animals, bizarre natural history specimens, and a Micrarium of microscopic creatures.

This shop and gallery is a modern-day cabinet of curiosities, unassumingly positioned along an urban thoroughfare.

A kaleidoscopic warehouse-maze of handmade neon signs.