Twice a day one of these tragic bronze mariners drowns with the tide to remember all those the sea has taken.

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

This vacant church in the Financial District was once the heart of New York's first Syrian immigrant community.

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

Unrepaired walls from a 1920 anarchist bomb attack.

Possible relics of the ancient Roman city are hidden in this restaurant's façade.

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

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

Once the tallest building in the world and the site of "the highest dinner ever held in New York" this building now holds the most expensive penthouse in the city.

Try not to get slimed in Tribeca.

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

The home of aviation trailblazers, in a remote corner of the big city.

A once crucial portion of the Long Island railroad still lays abandoned, waiting to be turned into an urban park.

Read between the lines of the subway map to find the hidden abandoned Civil War fort.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

A crumbling hospital from the 1850s on Roosevelt Island.

Hidden in plain sight on the Hudson River is an abandoned train station where nature has taken over.

Lie in a hammock where George Washington stood.

This abandoned seaside fortress is now simply an imposing ruin being taken back by nature.

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

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

The haunting, dilapidated remains of a former poorhouse on Staten Island's Greenbelt.

A tiny microvalley etched into the side of Knocknarea Mountain hides another world.

Mother Nature outdoes herself with this stunningly beautiful set of caves carved into marble.