These eerie outliers of the lightning bug family glow a mysterious blue color.

Bigfoot prints, Feejee mermaids, and haunted dolls on display in a tiny North Carolina town.

There's a piece of New York City transportation history hidden in plain sight at a Manhattan subway stop.

An accidentally hidden library containing the ephemeral history of New York.

Nope, not Washington Irving's house.

This slender three-story building has also had several famous residents.

The first piece of public art dedicated to LGBT rights.

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.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

A dilapidated dock tells the story of Titanic's missed arrival.

A hands-on traveling collection of the innovative devices of yesteryear.

A New York garbage depot holds a secret collection of weird and wonderful refuse.

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

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

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 house where the famed outlaw was shot by a dirty coward is now a museum to the criminal's legacy.

The world's largest collection of fine-scale miniatures and one the nation's largest collections of antique toys.

Giant granite rocks standing end-to-end like a train of circus elephants.

Community bookshelf of 25-foot-tall book spines.

The world's largest man-made underground caverns offer unparalleled underwater wonders.

After hundreds of years of settlement, this once-bustling fishing village sunk into the Chesapeake Bay.

The shelves in the back of this thrift store are devoted to saving, not selling, retro tech.