This medieval tower is all that remains of the castle where Joan of Arc was held before being burned at the stake.

The tombstone of an unfortunate explorer who disappeared in the Paris Catacombs.

The remains of the medieval wall that once surrounded Paris with ties to the construction of the Louvre.

This small, ingenious cannon once helped regulate Parisian life.

During the summer months, giant teddy bears take over Paris near Les Gobelins metro station.

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

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

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

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

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

A series of abstract, silly sculptures represent the works of a great modern classical composer.

The narrowest street in Paris.

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

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.

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

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

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

France's national museum of scientific and industrial instruments.

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

The vast, legendary catacombs hold secrets much stranger than stacked bones.

This candy-colored storybook village originated as a 19th-century Methodist campground.

This medieval castle was painted pink as part of a now-abandoned children's theme park.

This mansion on an island off the coast of Georgia once belonged to a 108-year-old heiress.