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

A small peaceful park and waterfall tucked amid the urban grind of Midtown Manhattan.

In the middle of downtown Brooklyn lies a 165 year old secret hidden right below the surface (closed to the public indefinitely).

This small, hidden cove is home to abandoned boats.

More than 250 sakes are available in an izakaya hidden in the basement of a Midtown office building.

Empty, but not abandoned, this cavernous Brooklyn loading dock was once considered the largest individual building in the world.

This abandoned seaside fortress is now simply an imposing ruin being taken back by nature.

Thriving meadows span a rooftop in one of Brooklyn's most heavily industrialized neighborhoods.

This subterranean oyster house has been the pearl of Grand Central Station since 1913.

Everyone from Mark Twain to Teddy Roosevelt has a pipe hanging from the walls of this historic chophouse.

The name of this tiny pocket park tucked between two buildings on Manhattan's Upper West Side is Latin for its location: "seventy-one."

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

Check out the underground party scene at the "Burning Man of Brooklyn."

Avoid gangster interaction while window-shopping.

This otherwise innocuous bodega was once the headquarters of the most feared assassin's guild in American history.

The oldest living tree in Manhattan comes shrouded in sinister legend.

A hyper-luxurious, 12,000- square foot home might be buried beneath Queens, still waiting to protect you from nuclear missiles.

Built as a gift to the hottest tastemaker of the time, these hidden quarters remain an Art Deco showpiece.

Deep under Manhattan is the largest construction project in city history. So far, the project has taken the lives of 23 workers, or "a man a mile."

The crown jewel of the Queens Museum is a nearly 10,000-square-foot architectural model of the city originally built for the 1964 World's Fair.

This collection of grinning ephemera has grown from basement to Brooklyn.

A WWI fighter plane and turn-of-the-century penny candy shop are among the unexpected features of this Financial District building.

This innocent-looking townhome is actually a subway exit.

Prove you deserve to be fed by Kenny Shopsin.