A commemorative plaque hides a door that leads down to the New York Public Library's underground book bunker.

The greatest real estate coup of all time.

Final resting place for the Triangle Shirtwaist fire’s unidentified victims.

The front yard of an Upper East Side town house hides the last fragment of one of New York's most famous theatres.

One of the oldest Jewish cemeteries in the city, it is now overgrown with an urban forest.

Crammed into several rooms of a Staten Island home, this museum is a vodka-soaked paean to the pleasures of drinking.

A way to take your secrets to someone else's grave.

A hidden "place of interment for gentlemen."

The first museum in the United States dedicated entirely to posters.

This small, hidden cove is home to abandoned boats.

A Victorian cemetery in the heart of Brooklyn remains a popular mecca of morbid curiosity.

Historical figures from New York City's Catholic community reside in Midtown.

The end of the 4 Line is also the end of the line for 300,000 souls in one of NYC's most illustrious cemeteries.

Abandoned power station once home to a squatter community, now being developed into an arts center.

Unlock the secrets of the conjuring arts.

The famous author's cottage hideaway.

Once the tallest building in the world and the site of "the highest dinner ever held in New York" this building now holds the most expensive penthouse in the city.

The final resting place of the great escape artist, where some still gather to wait for his escape from death.

The oldest operating apothecary in the US has treated everyone from Thomas Edison to Mark Twain.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

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

A crumbling hospital from the 1850s on Roosevelt Island.

This historic New Orleans cemetery is the final resting place of members of the Independent Order of Odd Fellows.

A typical "Old South" manor, once owned by author Anne Rice, served as the setting for several of her witchcraft sagas.