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

The narrowest street in Paris.

This 400-year-old tree is actually an immigrant from North America.

A surrealist timepiece by the artist of melting clocks.

The remaining relics of the patroness of Paris lie in a chapel under a striking double spiral staircase.

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

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

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

Site of a classic 19th-century physics experiment to prove the earth is rotating.

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

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

This tower is one of the best-preserved (and least-visited) remnants of medieval Paris.

Executions were once held near this beautiful 18th-century fountain.

This small, ingenious cannon once helped regulate Parisian life.

Behind the pink curtain, Au Bonheur du Jour, an art gallery of erotic archives.

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

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

A lush vertical garden blooming in the heart of Paris.

This stone angel is one of the biggest caryatids in all of Paris.

This banal Parisian entranceway is not what it seems.

The location of this small park was once the site of an infamous public morgue.

A legend says that if this elaborately decorated glass breaks, the good fortune of its owner's household will also disappear.

The pockmarks across the building's facade are remnants of the Blitz.

Legends say that this Art Deco apartment building almost became Hitler's British headquarters.