A counter-culture bookstore like no other hides in plain sight in the streets of Paris.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

A haunting collection of the vanished and disappearing natural world.

One of the oldest medical collections in Europe focusing on rare surgical instruments.

The very center of Paris is surrounded by a bevy of strange good luck rituals.

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

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

A museum of carnival attractions where you are invited to ride the rides.

Abandoned railway line circling the city of Paris.

Notorious artist squat renovated into legal studios.

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.

Never actually a tree at all, this spot was the site of London's public hangings for nearly 600 years.

This secluded walkway overlooks a magnificently wild London green space.

On October 17, 1814, a 15-ft. wave of beer ran rampant through the streets of London.

A plaque hangs near the execution place of the Scottish Independence leader famously depicted in "Braveheart."

This home on a quiet suburban street is completely covered with vibrant mosaics.

Charles Babbage's proto-computer, painstakingly brought to life.

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

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

The quaint little store that is said to have inspired a famous Dickens novel was only given its name after the book was released.

Several plaster noses are hidden in plain sight around London's Soho neighborhood.

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