One day a year it is legal to jump off of this astoundingly tall bridge that spans an Appalachian gorge.

Hikers can still stroll beneath the long conveyer of this abandoned mining facility hidden in a West Virginia river gorge.

Once connected to the outside world by a single train track, this ghost town is looked after by the National Park Service.

The resting place of a Civil War celebrity's amputated limb.

The Kirkland Monument remembers a selfless Civil War hero who braved the battlefield to give water to his dying enemies.

A home that witnessed Civil War combat on the Sunken Road has the battle scars to prove it.

This evocatively named natural crevasse was created by a torrent of water that smashed right through a granite deposit.

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

A forgotten relic from New York's bygone trolley system hides in plain sight under a bridge.

Site of the first pathological and bacteriological research facility in the United States.

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

A crumbling hospital from the 1850s on Roosevelt Island.

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

There are owls with glowing eyes in Herald Square.

A bit of retro transportation flair preserved in the world's largest department store.

Hidden in plain sight on a pair of Manhattan subway tunnels are a pair of public instruments that sing to each other.

The greatest real estate coup of all time.

This hollow steel globe is the second-largest in the world.

An ivy-covered arch bridge dedicated to Tejano music singer and legend Rosita Fernandez.

Three hundred years of preserved Spanish colonial history in San Antonio.

Legend has it the commander of the defenders drew a fateful line in the dirt with his sword just before the final battle.

This hidden sculpture garden full of Wild West art is one of San Antonio's best-kept secrets.

Canada's largest dinosaur skeleton was hidden away in storage for more than 40 years.

A 98-room castle in the middle of Toronto that bankrupted a 19th century electricity multimillionaire.