Oldest surviving example of a Dutch saltbox frame house in America.

One of only two remaining Victorian-era greenhouses in New York.

One-time largest man-made structure in the world will be a park in 30 years.

Beneath the mossy overgrowth covering this once-sprawling campus lies decades of history and the secrets that come with it.

Check out the underground party scene at the "Burning Man of Brooklyn."

A fire station-turned-church-turned-museum dedicated to the work of seminal light artist Dan Flavin.

A mysterious air force base built to resemble a Long Island fishing village.

A tiny islet just off Long Island offers a wealth of infectious curiosities.

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

The most unloved grain elevator in Brooklyn was a “Magnificent Mistake.”

A community farm in the midst of the Brooklyn concrete.

“Invented in Key West, Perfected in Brooklyn."

In its day this historic fort held 100 cannons pointed in almost every direction to protect New York.

A mysterious, abandoned building rotting on the Brooklyn waterfront.

The Vatican of the movie industry turned into an actual church.

A temple belonging to the largest Buddhist order in South Korea nestled in the middle of New York City.

The oldest continuously operating farm in New York State.

This outpost of America's most popular fast-food restaurant is housed inside a palatial mansion.

The abandoned grounds and derelict greenhouses of this once-magnificent Edwardian estate are now a nature preserve open for exploration.

All that remains of a magnate's dream home is a historic gate and an abandoned public pool.

An abandoned Gold Coast-era mansion once intended for the exiled ruler of Albania, who never arrived.

A formerly abandoned mental institute, now back in business.

Just your average Marie Antoinette–themed speakeasy in an abandoned 19th-century subway tunnel.

This narrow shop in the East Village hosts a matchmaking service for the new millennium.