This outdoor gallery of graffiti-covered walls pays homage to the past, present, and possible future of street art.

Touching mementoes from those who didn't make it back from World War I still hang in one of New York's oldest bars.

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

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

The former hotel where Tesla invented the radio.

Unrepaired walls from a 1920 anarchist bomb attack.

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

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

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

Avoid gangster interaction while window-shopping.

Spinning silently in the lobby of an Art Deco masterwork is a massive vintage model of the Earth.

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

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.

Prove you deserve to be fed by Kenny Shopsin.

Once America's longest-manned military fort, now an abandoned hulk.

Manhattan's lighthouse, erected at the insistence of the unsinkable Molly Brown.

A charming "tea atelier" hidden away in Greenpoint, Brooklyn.

Long the exclusive domain of birds and vagabonds, this little-known Central Park peninsula is open to the public once more.

This enormous Hindu temple in Queens serves incredible dosas in its basement canteen.

This semi-hidden Manhattan restaurant is based out of a loading dock.

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

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

Behind a bodega is a small museum of relics and ephemera showcasing the history of New York.

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