The oldest surviving synagogue in New York City is now a soaring art space.

The oldest bibliophilia club in America, with exhibitions on historic books and graphic arts.

The name of this famed hospital was once a byword for the horrors of medical and psychiatric care.

Great place to have a drink and a bite to eat in an atmosphere laden with New York's Bohemian past.

An unrealized dream to wirelessly electrify the entire Earth.

The world's oldest hologram gallery and the labyrinthine laser laboratory of a holography pioneer.

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.

A three-story copper skybridge connects two Manhattan buildings with Art Deco luxury.

Ride the subways of yesteryear.

An unassuming secret door once led to a legendary watering hole.

One of the last few places in Manhattan that employed a pneumatic systemic keeps it on display.

Read between the lines of the subway map to find the hidden abandoned Civil War fort.

This unmarked and unloved Manhattan subway grate created one of the most iconic images in American cinema.

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

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

Home to the infamous "Typhoid Mary" and the worst loss of life in New York's history prior to September 11, 2001.

Hidden in an ordinary Midtown building is a one-room museum dedicated to the greatest escape artist.

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

Peek through the gates at this oasis from the city, full of Old English charm.

New York City's smallest piece of private property.

This lower Manhattan bar is set up in an old bank vault that rests beneath a skyscraper that hides even more historic splendor.

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

A natural gas leak provides a flickering flame beneath a waterfall.

The feral felines of Roosevelt Island have a small army of allies and an abandoned hospital all to themselves.