Unrepaired walls from a 1920 anarchist bomb attack.

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.

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

An artist's cute bronze subway sculptures belie his violent artistic past.

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

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

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

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

Wall Street has a new heroine, a bronze statue of a small but fierce girl.

Cryptic messages embedded in the New York City sidewalk.

This abandoned subway station can still be seen on regular commuter trips.

Bowl in splendor, if you're lucky.

A masterpiece of LGBT art has been restored in what may now be the most valuable restroom in America.

Wine bottle sculpture with a ship's stateroom inside.

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

The oldest house in Manhattan is now a museum that remembers the home's sordid history of scandals, vice-presidents, and ghosts.

This whimsical group of statues is a favorite of children who love to climb all over Lewis Carroll's beloved characters.

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

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

Plot your trip through the city on the sidewalk.

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 popular European tradition makes its way to the states on one of America's most famous bridges.

A clock set into the concrete outside a Manhattan jeweler has been telling time underfoot for over a century.

For over 30 years the walls of this Harlem schoolyard have been a gallery of street art by "Kings and better."