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

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

A crumbling hospital from the 1850s on Roosevelt Island.

This beautiful building in the heart of Manhattan's Financial District was empty for decades.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

Currently housing a corporate bank branch this building at the southern tip of Manhattan was once the gateway to luxury vacationing.

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

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

This Wall Street bar was once a hub of revolutionary activity where Washington famously bid farewell to his troops.

Amid the bustle and noise of the Financial District hides a secluded garden oasis above the city streets.

A commemorative plaque hides a door that leads down to the New York Public Library's underground book bunker.

The fanciest public restroom in New York City boasts fresh flowers, art, and a classical music soundtrack.

A terrific purveyor of natural history objects and curios.

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

A glamorous hotel that once accommodated French resistance fighters and concentration camp survivors.

Lady Liberty's first beacon of enlightenment is now displayed in a museum near the statue.

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

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

Elevated freight railway turned wildly successful urban park.

Dolls of all shapes and sizes display the eras of femininity in this spooky and beautiful collection.

A tribute shrine where the Space Invasion street art movement started.

If you look closely at the oldest bridge in Paris, you might notice hundreds of ugly faces leering from its sides.

During the summer months, giant teddy bears take over Paris near Les Gobelins metro station.

The video game-themed street art first popped up in the French city.