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

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

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

A haunting collection of the vanished and disappearing natural world.

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

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

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

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

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.

The oldest stone house in Paris was built by its most famous alchemist.

Abandoned railway line circling the city of Paris.

Notorious artist squat renovated into legal studios.

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

Collapsed television tower finds new life as a control tower for boat races.

A curious urban windmill once owned by a renowned British mathematical physicist.

These 90-year-old murals of local kings, Vikings, and outlaws hide in plain sight in a beautifully baroque shopping arcade.

The English Civil War began right here in 1642.

There's a labyrinth of medieval chambers hidden deep below a 15th-century pub.

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

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

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

The oldest inn in England served brew to the crusaders.

Claiming to be the oldest hat store in the world, this historic haberdashery had a hand (and a head) in the creation of the Bowler.