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

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.

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

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

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

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

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

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.

A slice of central Asia in the middle of Berlin.

This sprawling Jewish cemetery is one of the largest in Europe.

The skeletal frame of a decommissioned gas-pumping station offers breathtaking views of greater Berlin.

Metro station with a claim to rock n' roll fame.

A monument to the man who almost killed Hitler.

Beneath the impressive baroque cathedral that rises from the center of Berlin lies the largest collection of Prussian royals in the world.

From toys to kettles to scientific instruments, this German museum celebrates the beauty of 20th century design.

The building is a gigantic piece of art inspired by the shape of a desert rose.

This small 16th-century church in Athens is almost entirely surrounded by a modern building.

An unusual ode to the late Irish playwright, complete with a squiggly bust and coffin-shaped bench.

Installed at a chaotic intersection, this gave London traffic cops a place to hang their heavy woolen coats.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

A statue of the original Pearly King is hidden in a church's crypt.