BDSM, 1930s Style.

This museum in a Paris apartment gives a unique look at the iconic French singer's life.

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

This banal Parisian entranceway is not what it seems.

The former home of France's controversial pop maestro is almost completely covered in ever-changing tributes and graffiti.

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

A modern-day Lascaux cave underneath Paris.

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

The subterranean "lake" below the Paris opera house inspired the Phantom of the Opera's lair.

The curious underground history of keeping Paris clean.

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

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

Egyptian Revival movie palace abandoned for decades and restored in 2013.

A favorite Paris bar for U.S. expats, including Gershwin, Hemingway, and James Bond.

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

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.

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

This massive library holds what was once the largest book collection in the world.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

This beautiful building in the heart of Manhattan's Financial District was empty for decades.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

A crumbling hospital from the 1850s on Roosevelt Island.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

This "life-size" depiction of Mickey Mouse as a half-lobster is both whimsical and a bit creepy, standing guard over the Boston waterfront.