Where now stands a 42-story condominium tower of marble, glass and steel was once the central market of New York’s slave trade.

The 28-foot granite map plots the locations of 40 theaters in New York City.

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

Down a stairway in the East Village, you could once read a plaque describing an alternate history of a fictional version of Manhattan.

This was one of the first (and last) university-built and operated nuclear reactors.

The artist and New York City icon lived, worked and died in this converted carriage house owned by another iconic artist, Andy Warhol.

This exemplar of modernist architecture is meant to captivate and inspire students of the Cooper Union.

Discover the taste of mold.

A posh members-only club with a literally dramatic history.

The most confusing clock in New York.

Built hundreds of years ago this downtown iron barrier once protected a much despised king.

Visit the site of a subway powered by nothing more than air--and lots of it.

A notorious punk house turned co-op.

In its day this historic fort held 100 cannons pointed in almost every direction to protect New York.

A Manhattan office building is home to the world's largest chess board.

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

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

An odd, ancient window that may have once been part of a brutal prison is embedded in the side of New York's Police Plaza.

A whimsical, but often overlooked clock in Park Avenue.

This wall on a street corner in Lower Manhattan has been a blank canvas for a rotation of renowned artists since the 1980s.

Unrepaired walls from a 1920 anarchist bomb attack.

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

A bit of retro transportation flair preserved in the world's largest department store.

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."