A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.

The floorboard scrawling of a tragic madman is on public display outside a Paris hospital, much to the dismay of its opponents.

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

The recovered bones of martyrs slaughtered during The Terror are on display in this church crypt.

Museum on French naval history, with magnificent figureheads, a historic diving suit, and a boat used by Napoleon.

A popular shrine where the Blessed Virgin allegedly appeared in 1830, displaying a holy armchair and two incorruptible remains of Lady Saints.

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

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

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

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

A lone cannonball remains lodged in the walls of the Hotel de Sens as a sober reminder of a revolution.

Hidden away in a modern library are the remains of one of the 18th century's most celebrated wunderkammers.

Natural history museum celebrating biodiversity with a parade of taxidermy animals.

This former “ante-chamber to the guillotine” has been refurbished to illustrate the brutal history of French justice.

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

The first green space constructed on an elevated viaduct.

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

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

The history of radiation is on safe display at the foot of a radiation science laboratory.

Down a cobblestone alleyway is a museum dedicated to Romanticism, with a secret garden.

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.

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

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