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

This recessed garden protects thousands of mountain plants by creating its own microclimates.

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

The spiral staircase hidden inside this giant Parisian column was likely built for Catherine de Medici's astrologer.

This Parisian gem is one of the most incredible ethnographic museums in the world.

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

Despite being considered a thoroughly American sport, basketball's oldest surviving playing field is found in the basement of a Paris YMCA.

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

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

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

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

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

An iconic and eccentric bar for "Manouche" Jazz music keeps expanding its space—and its influence.

This structure atop a craggy cliff in one of the most beautiful parks in Paris boasts an unbeatable view.

This off-limits room in the National Library of France is home to a system of pneumatic tubes, once used to bring books to readers.

Noirish green neon marks the location of one of the oldest private detective agencies in France.

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

An immersive projection art installation uses sound, scale, and light to take visitors inside classic works of art.

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

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

This banal Parisian entranceway is not what it seems.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

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

This life-size replica of the Statue of Liberty's flame is also a tribute to Princess Diana by default.