The world’s largest underground marble quarry is hiding in Vermont.

An ancient glacial pothole waterfall in the heart of the Green Mountains.

This cavernous abandoned marble mine is popular with ice skaters in the winter.

Tour the world's largest deep-hole dimension granite quarry, where you can view the plant where gravestones are made and roll a ball down the outdoor granite bowling alley.

Not even a series of devastating fires could keep this odd castle in upstate New York from bouncing back.

These World War I shooting range tunnels are now haunted halls of underground graffiti accessed through the roots of a tree.

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

Protecting the future of some of the rarest and most misunderstood mammals of North America.

What was once a trend-setting, phrase-coining icon of architectural splendor is now a rotting, forgotten hulk.

The site of a tragic massacre that spawned a multimedia franchise.

In upstate New York, gorgeous waterfalls and a watermill are slowly being reclaimed by nature.

The first and only carousel with a lineup entirely of insects.

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

An abandoned asylum where patients have been forgotten but their possessions remain.

A natural gas leak provides a flickering flame beneath a waterfall.

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

A restaurant on Staten Island showcases a different grandmother’s cooking every night.

The abandoned husk of a mental institution that failed to save a Jazz Age icon still sits nearly unchanged.

The oldest operating apothecary in the US has treated everyone from Thomas Edison to Mark Twain.

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

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

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

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

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.