An architectural oddity hides in plain sight on this iconic London bridge.

Traveling collection of amazing automata.

This pub was 238 years old when it decided to revamp its image: It started serving Thai food.

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

A statue marks the exact spot where The Boy Who Never Grows Up made his first literary appearance.

Hidden behind a wall for decades, this masonic lodge was only rediscovered during renovations.

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

A 300-year-old tea shop that brought tea to the English people, not to mention the Queen herself.

This Arabesque Italian castle was built with a primitive, if ingenious, air-conditioning system.

If you look closely at the oldest bridge in Paris, you might notice hundreds of ugly faces leering from its sides.

This bridge was constructed from the rubble of the infamous Bastille.

This Parisian gem is one of the most incredible ethnographic museums in the world.

The former home of France's controversial pop maestro is almost completely covered in ever-changing tributes and graffiti.

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

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

Original cabaret handbills, posters, and feline artwork are a purrfect highlight of the Museum of Montmartre.

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

A surrealist timepiece by the artist of melting clocks.

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

Notorious artist squat renovated into legal studios.

This restored Portuguese cafe may well be the most beautiful place in the world to grab a Big Mac.

A hidden three-foot-wide house separates these two regal churches.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

A long-buried ancient ruin unearthed right in the middle of the city.