Love is in the air along the small street in Brooklyn.

This block in downtown Brooklyn was a hotbed of antislavery activism along the Underground Railroad.

This striking arch, one of the first architectural elements constructed in Prospect Park, was recently restored to its original glory.

This city park was once a lookout point for George Washington’s army during the Battle of Brooklyn in 1776.

A modern zoetrope on the New York City subway.

19th century cemetery hidden in Brooklyn's Prospect Park.

This secluded ruin was once a home for exotic plants.

Avoid gangster interaction while window-shopping.

The New York hotel where tragic visionary Nikola Tesla spent his final hours, destitute and alone but for the pigeons.

A tunnel once abandoned now thrives with graffiti art as an off-limits makeshift gallery.

On the top floor of an upscale department store stands a lavish restaurant housed in a replica of a luxury French dining car.

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

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

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

Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

Manhattan's Thirteenth Avenue was made on landfill then deliberately destroyed — apart from one small, obscure block.

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 crumbling hospital from the 1850s on Roosevelt Island.

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."

A terrific purveyor of natural history objects and curios.

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

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

Discover the taste of mold.