There's a piece of New York City transportation history hidden in plain sight at a Manhattan subway stop.

One of only two commuter aerial tramways in the United States.

On the top floor of an upscale department store stands a lavish restaurant housed in a replica of a luxury French dining car.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

A former insane asylum despised by Nelly Bly and Charles Dickens is now fashionable apartments.

This ruined fort hidden at the top of Central Park can't seem to keep from losing its historical plaques.

A plaque immortalizes the spot where the early American spy said his famous last words: "I only regret that I have but one life to lose for my country."

A collaborative art project that transformed a neighborhood in NYC's Queens.

Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

This whimsical group of statues is a favorite of children who love to climb all over Lewis Carroll's beloved characters.

The walls are decorated with whimsical murals painted by the creator of the Madeline franchise.

A little lighthouse in New York City, surrounded by mysterious stories of insanity-driven construction.

New York's oldest and possibly grandest keeper of books.

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

For over 30 years the walls of this Harlem schoolyard have been a gallery of street art by "Kings and better."

This hidden library of physiological ephemera contains centuries worth of knowledge on the vim and viscera of the human body.

A New York garbage depot holds a secret collection of weird and wonderful refuse.

Unique antiquarian shop specializing in globes, maps, and prints.

Beautiful mosaics cover the first stations opened on New York City's newest subway line.

A historic 1890s architectural masterpiece with an iconic clock tower that, once open to the public, now faces an uncertain future.

An accidentally hidden library containing the ephemeral history of New York.

A partially hidden wall graffitied by spectators of the 1976 Bicentennial, recently rediscovered.

An artist's cute bronze subway sculptures belie his violent artistic past.

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.