A wunderkammer hidden on the top floor of the Hartford statehouse.

More gold than anywhere else, ever.

An unassuming secret door once led to a legendary watering hole.

The phone booths of New York City have all but disappeared, but their remains were once found in this "graveyard," sadly now removed as well.

This derelict building used to house infirm Freemasons, their widows, and orphans.

A hyper-luxurious, 12,000- square foot home might be buried beneath Queens, still waiting to protect you from nuclear missiles.

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

The "Seinfeld" diner.

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

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

Harlem park dedicated to compulsive hoarders killed by their own junk.

The only home that Alexander Hamilton ever owned has a history almost as troubled as his own.

From scholastic to sepulchral - now under reconstruction.

Hordes of precariously balanced stone figures crowd the shores of the Hudson River.

Little Red Lighthouse under the George Washington Bridge.

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

The highest point on the island known for buildings that touch the sky.

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

The first "Hall of Fame" in America was designed by legendary Gilded Age architect Stanford White for what was then the NYU uptown campus.

A large boulder marks the place where the island of Manhattan was purportedly "sold" to the Dutch.

The famous author's cottage hideaway.

This once-grand marvel of engineering is now 41 miles of scenic hiking trail.

Small monoliths of several varieties of stone sit alongside a wooded path in the Bronx.

An abandoned horticulture institute gloomily presides over rows of derelict and vine-wrought greenhouses.