Oldest existing church in New York and the inspiration for Washington Irving's "The Legend of Sleepy Hollow."

Blighted Irish field and the ruins of a 19th-century cottage on the edge of urban Manhattan.

The oldest house in Manhattan is now a museum that remembers the home's sordid history of scandals, vice-presidents, and ghosts.

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.

An abandoned asylum where patients have been forgotten but their possessions remain.

An abandoned town is hidden in Great Smoky Mountains National Park.

More than five miles of underground passageways.

Wild lights and sound effects turn a walk through some caves into an eye-popping 1960s tourist attraction.

For two weeks every June, fireflies in the Smoky Mountains perform an astonishing light show.