This old cement mine has been used as everything from a mushroom farm to a recording studio.

This former theme park in New York's Adirondack Mountains fell into ruin before being resurrected as a state-run campground

The library of every book lover's dreams.

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

New York's oldest and possibly grandest keeper of books.

The beautiful tunnel that ran from the lobby to Penn Station is still hidden underneath 34th Street.

Unique antiquarian shop specializing in globes, maps, and prints.

A band of aerialists and circus performers putting on incredible shows in East Williamsburg.

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

Nondescript elevator doors open to reveal a stunning, surreal world.

An abandoned castle owned and ignored by Masons carries a cursed history.

Become a prohibition rebel.

Mysterious 500-year-old tapestries depict a unicorn hunt.

A very classy 1920s-era bar right in Grand Central Station.

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

A stunning, two-tiered waterfall made famous by poets, artists and the legend of a ghost dog.

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

The world’s oldest and biggest bookstore stocking only mystery, crime fiction, espionage, and thrillers.

The site of the first "historically true" UFO encounter in the U.S.

An enormous, inside-out glass globe built in 1935.

This small, unassuming, nursery plays hosts to some unique plant life.

This store also houses a museum dedicated to the history of these small, historic community shops.

The largest arcade museum in the world chronicles the golden age of video games which ended promptly in 1987.