Ancient paintings known as the "Sistine Chapel of Cave Art."

One of the greatest maze designer’s greatest mazes.

Sacked by Vikings, blessed by William the Conqueror, dealt a fatal blow during the French Revolution—these ruins have seen it all.

An off-the-beaten-path boutique stuffed with an eclectic collection of upcycled goods.

A majestic lion statue guards this Parisian botanical garden, and feeds on an unsettling item.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

Statue of death tucked in the University of Medicine courtyard.

The ruins of a Duke's bucolic dream, where camels once roamed alongside "Dutch" windmills and faux-Italian vineyards.

A museum on the history of Paris, including a set of Napoleon's toiletries, Proust's room, and relics of the Revolution.

Exquisite wall sculptures carved in secret by an early quarryman in an obscure corner of the Paris Catacombs.

Indents in the pavement are all that remain from a grisly death machine in Paris.

A surrealist timepiece by the artist of melting clocks.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

France's national museum of scientific and industrial instruments.

This museum houses an imposing skeleton army comprised of creatures great and small.

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

This Parisian café sticks almost exclusively to an ethos of reuse.

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

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.

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

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

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

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