The historic Masonic Lodge in which the first-ever female Mason was initiated.

This bridge was constructed from the rubble of the infamous Bastille.

This banal Parisian entranceway is not what it seems.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

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

135 bronze medallions mark a French meridian line which once rivaled the hotshot Greenwich timeline.

The headless bodies of more than 1,300 guillotined victims of the Reign of Terror are buried here in mass graves.

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

The subterranean "lake" below the Paris opera house inspired the Phantom of the Opera's lair.

A modern-day Lascaux cave underneath Paris.

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

Two awe-inspiring globes from the reign of the Sun King hang from the ceiling of France's national library.

The former home of France's controversial pop maestro is almost completely covered in ever-changing tributes and graffiti.

Pitié-Salpêtrière was the dumping grounds for women who received the dreaded diagnosis of "hysterical."

In the best of all possible worlds, everyone will get a chance to see this statue in which Voltaire's heart is interred.

A Parisian exterminator's shop whose storefront displays stuffed rats hanging from traps.

A subterranean shelter remains intact under a busy Paris railway station.

The curious underground history of keeping Paris clean.

This Parisian fountain is a little bit fantasy and a little bit nightclub.

The largest medical and anatomical collection in France lies hidden from the public.

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

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

Known as the "Dodo Manège," this carousel features a herd of animals that have disappeared—or may be gone soon.

Statue of death tucked in the University of Medicine courtyard.