A 400-year-old church covered floor to ceiling in ex-voto offerings from the faithful.

An odd museum dedicated to French fakes.

The personal library of the founder of modern neurology is open to visitors.

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

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

This little-known relic crypt holds stolen parts of a Roman Empress.

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

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

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

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

A unrivaled and rather horrifying collection of wax dermatological models.

The first green space constructed on an elevated viaduct.

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

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

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

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

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

A surrealist timepiece by the artist of melting clocks.

Walk upon the mementos of the dead in this Parisian courtyard paved with medieval tombstones.

A haunting collection of the vanished and disappearing natural world.

The oldest stone house in Paris was built by its most famous alchemist.

A plaque marks the house in Stockholm where the French philosopher René Descartes lived up until his death.

An ancient Viking runestone hidden in plain view in Stockholm's old town.

The library's graceful rotunda is like a bibliophile's temple.