Why have you never heard of the second most popular tourist site in New York?

Discovered by cows, these upstate New York show caves are presented with a healthy dose of psychedelic folk art.

This backwater graveyard in the Hamptons became a trendy burial spot and posthumous status symbol for famous artists.

A beautiful, historic location open to the public.

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

A beautifully designed asylum was resurrected as a hotel and art center with a ghost story or two.

A ruined mansion hidden in the woods of the Hudson Valley, home of a tragically doomed romance.

The name of this famed hospital was once a byword for the horrors of medical and psychiatric care.

This Queens hospital has stood abandoned for almost 20 years after its patients were secretly relocated in the dead of night.

Abandoned 19th century homes once occupied by naval officers, soon to be demolished.

First a horse rendering plant, then a 19th century landfill, this beach is full of glass from thousands upon thousands of broken bottles.

This former water source for the City of Brooklyn is now a thriving natural wetland.

Staten Island's original central park is the former home of the city water supply as well as thousands of immigrant graves.

Final resting place of Typhoid Mary.

The humble fort that saved Washington.

This preserved wilderness hides the remains of a colonial grain mill used to feed George Washington's troops.

The Underground Railroad passed right through this historic Brooklyn Heights church.

Revolutionary War casualties fill the only 17th century structure remaining in Manhattan.

You must take the A train... to the last active cemetery in Manhattan.

A former connection to City Island, it has been abandoned since the 1930s.

One of the oldest Jewish cemeteries in the city, it is now overgrown with an urban forest.

19th century cemetery hidden in Brooklyn's Prospect Park.

A Manhattan Episcopal church with an eerie underground crypt.

This small, hidden cove is home to abandoned boats.