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.

A living archive of urban activism and space reclaimed.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

One of only two commuter aerial tramways in the United States.

The feral felines of Roosevelt Island have a small army of allies and an abandoned hospital all to themselves.

A semi-scholarly approach to sex.

Elevated freight railway turned wildly successful urban park.

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."

A crumbling hospital from the 1850s on Roosevelt Island.

The massive machine creates cracking displays of indoor lightning.

Berthed at the Charlestown Navy Yard in Boston, "Old Ironsides" is the oldest commissioned warship still afloat.

The 340-year-old house that inspired the classic Nathaniel Hawthorne novel.

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

A grave surprise in the downtown area of New England's second-largest city.

A comic book store got the road by its shop officially renamed after Superman's girlfriend.

The Burnside Fountain and its questionable interpretation.

This miniature feudal castle was built on a whim to honor a US Navy pioneer.

A religious-themed park filled with folk art to bring biblical stories to life that fell into disrepair and now being restored.

At this farm in upstate New York, the former president plotted his reelection campaign.

The original Uncle Sam was actually a New York meatpacker who is buried under this historic grave.

This giant monument of the RCA mascot is a beloved fixture in Albany, New York.

The first American home of the isolated, egalitarian religion has a trove of Shaker architecture and artifacts.