What looks like a normal building is really a hollow facade hiding a subway vent.

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

Where the high court feasted, frolicked, and high courtesans put their royal lovers' diamonds to the test.

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

The oldest continuously operating mint in the world that has been making coins since the 9th-century.

This frog-themed restaurant was frequented by Picasso, Saint-Exupéry, and more.

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

A poem by Arthur Rimbaud is inscribed on the wall of a street that, while it is only one block long, plays a key role in multiple novels.

This 18th-century sundial was designed to calculate the date of Easter each year.

An unusual number plate signifies the building's saucy past.

A museum dedicated to linguistics, from how babies learn to talk to endangered and extinct languages.

The celebrated eyesore created by starry-eyed sweethearts.

The approximate spot where the last Grand Master of the Knights Templar was put to death.

A surrealist timepiece by the artist of melting clocks.

The video game-themed street art first popped up in the French city.

The narrowest street in Paris.

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

With a history of slaughter, feast, and famine, remnants of the pork industry decorate this area--even its church.

Beggars were miraculously "cured" of their fake ailments when they returned home to this 17th century Paris slum each night.

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

The curious underground history of keeping Paris clean.

A beautiful Victorian statue shows France's enduring love of the rhinoceros.

A French artist's vague warning hangs over Belleville.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the 20th century.