Need to book a room at the Hotel Pennsylvania? Just dial up 6-5000.

A dark patch of the ceiling at Grand Central Terminal which was not restored is still stained brown by tobacco.

A DIY art gallery/music venue/lecture hall dedicated to video game culture.

The "Seinfeld" diner.

During the holidays, a vintage subway train whisks New Yorkers back in time.

There’s a secret bunker inside the Brooklyn Bridge, but the city won’t say where.

Phil Mortillaro uses keys to bring art back to the Village.

The site of the deadly Triangle Shirtwaist Factory Fire.

A discreet little stairway on St. Nicholas Avenue leads to a quaint and unexpected cobblestone street of 19th century wooden rowhouses.

The beautiful tunnel that ran from the lobby to Penn Station is still hidden underneath 34th Street.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

Hidden in one of New York's oldest subway stations is the final remnant of the site of the bizarre Shakespeare Riots.

Love, knishes, and best wishes from this legendary Lower East Side bakery.

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

Avoid gangster interaction while window-shopping.

A curious fountain that has no water and includes Satan, a crab, and 9 giraffes.

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

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."

A dark, dank room in subterranean Manhattan was the site of a ghastly murder.

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

Hidden in plain sight on a pair of Manhattan subway tunnels are a pair of public instruments that sing to each other.

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

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

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