Paris' linguistic guide to the international language of, yes, love.

Notorious artist squat renovated into legal studios.

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

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

This massive library holds what was once the largest book collection in the world.

France's most famous cemetery, with some of its most curious tombs.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

Collection dedicated to brands, packaging and advertising.

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

A collection of comics, graphic novels, animation and caricatures devoted to exploring this often overlooked art form.

The world's first underground farm is in a World War II bomb shelter beneath the streets of London.

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

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

This collection of illusory paraphernalia has been culled from the history of London's premier magician's club.

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

The yawning maw of this pagan visage is said to bite off the hands of liars.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

A kaleidoscopic warehouse-maze of handmade neon signs.

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

This churchyard arbor is surrounded by hundreds of gravestones placed there by author Thomas Hardy.

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

The most visited, and possibly most controversial, museum in Germany.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.