A derelict bit of transportation infrastructure hidden in the woods.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

An Industrial Revolution-era public work that purified water using nothing but sand.

This former theme park in New York's Adirondack Mountains fell into ruin before being resurrected as a state-run campground

An old abandoned mining town in The Adirondacks where Theodore Roosevelt first learned of the shooting of President William McKinley.

The Hudson River School comes alive at this palatial estate.

A beautiful multicolored mound formed by the mineral deposits of the Orenda Spring.

The first evidence of some of the Earth's earliest life was found in this fossilized undersea grotto.

Fossilized sea bottom and lime quarry.

A mysterious echo seems to defy the laws of acoustics.

A peaceful international sculpture garden in upstate New York.

Decades after testing the polio vaccine on unwitting patients, this historic mental hospital sits in ruin.

One of the world's largest model railroads is a mind-boggling achievement.

The headquarters of the Fraternitas Rosae Crucis, complete with Rosicrucian pyramids, all in the Pennsylvania woods.

A pride of the state, this working museum crafts pottery mosaics in the style of Pennsylvania's earliest European settlers.

Eccentric concrete mansion and museum designed and built by hand from the inside out.

The home and studio of a visionary woodworker now stands as a museum and example of his artistic genius.

Delicate Wurlitzers, creepy clowns, and The Noid all share space in this insane explosion of kitsch history.

North America’s largest collection of horological devices and home to a colossal clock with a dizzying array of features.

One of the oldest Catholic churches in the U.S., situated just east of Gettysburg.

A modern ghost town whose inhabitants were driven away by the growth of nuclear power.

What looks like a simple quaint estate in rural Pennsylvania was in the 18th century home to a small monastic community.

The oldest farmer's market in America is so ancient it was approved by the King of England.

The home of possibly the least-loved U.S. president stands as a sort of unpopular Monticello.