Cryptic messages embedded in the New York City sidewalk.

Curious crustaceans support an obelisk from ancient Egypt that now stands in modern-day Central Park.

Wine bottle sculpture with a ship's stateroom inside.

Lie in a hammock where George Washington stood.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

A living archive of urban activism and space reclaimed.

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

Blighted Irish field and the ruins of a 19th-century cottage on the edge of urban Manhattan.

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

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

Unlock the secrets of the conjuring arts.

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

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

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

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

A historic 1890s architectural masterpiece with an iconic clock tower that, once open to the public, now faces an uncertain future.

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

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

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

Peek through the gates at this oasis from the city, full of Old English charm.

Mysterious 500-year-old tapestries depict a unicorn hunt.

Hidden in an ordinary Midtown building is a one-room museum dedicated to the greatest escape artist.

One of only two commuter aerial tramways in the United States.

A room in New York City that contains 250 cubic yards of dirt worth a million dollars.