This 29-ton granite ball spins around at the slightest touch thanks to a scientific phenomenon.

A convincing little bit of ancient Egypt smack dab in Richmond, Virginia.

This museum devoted to the gothic author holds such interesting ephemera as his socks and walking stick.

Hundreds of glow-in-the-dark objects light up a museum in a historic zinc mine.

Cleveland's giant "free" stamp is a nod to the Civil War, but was misinterpreted for years.

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

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

A room in New York City that contains 250 cubic yards of dirt worth a million dollars.

Reverend Jen's unique museum/living room showcases her troll collection.

Down a stairway in the East Village, you could once read a plaque describing an alternate history of a fictional version of Manhattan.

A masterpiece of LGBT art has been restored in what may now be the most valuable restroom in America.

Cryptic messages embedded in the New York City sidewalk.

The world's oldest hologram gallery and the labyrinthine laser laboratory of a holography pioneer.

A quiet and contemplative oasis in the middle of New York's bustle and riot.

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

A posh members-only club with a literally dramatic history.

Tucked away amidst some of the most famous addresses in the world is New York's only fraction of a street.

Built as a gift to the hottest tastemaker of the time, these hidden quarters remain an Art Deco showpiece.

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

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

This semi-hidden Manhattan restaurant is based out of a loading dock.

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

This innocent-looking townhome is actually a subway exit.

A treasure trove of artifacts, books, and artwork from the "golden age" of exploration.