One of the last few places in Manhattan that employed a pneumatic systemic keeps it on display.

This huge work of functional public art replaced a landfill in New Jersey's Meadowlands.

Edison's cast-in-place concrete houses were a failure, but way ahead of their time.

Secluded amid upstate New York’s Adirondack Mountains lies this subterranean emblem of a nation on the brink of nuclear war. And it's for sale.

A former infectious disease laboratory chronicles how tuberculosis shaped a village nestled in the Adirondacks.

Dozens of houses in the Adirondack Mountains are reminders of a literal "cottage industry" to cure people of a deadly disease.

A billionaire heiress' menagerie of animals were lovingly laid to rest on the grounds of her former estate.

American involvement in World War I officially ended in 1921 in New Jersey, three years late and thousands of miles from the battlefield.

The highest point in Tennessee, Clingmans Dome bears witness to the ravages of one type of insect.

This road in the Great Smoky Mountains was supposed to assuage a displaced community, but ended up a $52 million dead end.

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

Home of a 28-foot tall stalagmite known as the War Club.

This shale formation along the Appalachian Trail once inspired the third president of the United States.

This gruesome biblical parade celebrates the one day a year that a bit of Jesus' blood turns to liquid.

An Oklahoma museum that celebrates the history of the "Mother Road."

A historic covered bridge is but one example of an oddly prevalent American urban legend.

Not one, but two of Frank Lloyd Wright's architectural masterpieces nestled on the same street.

One New Hampshire alleyway has become home to a public gallery of feline art.

Once a sewer culvert, this road tunnel now offers cyclists and pedestrians a subterranean stroll under the C&O Canal.

Press 1 for knock-knock jokes.

Washington's top-secret Cold War-era doomsday communications tower is located in a small neighborhood park.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

The largest cemetery in the American Southeast is a hidden gem near the heart of Atlanta.

A 90-year-old underground water reservoir offers a more industrial kind of tranquility.