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

These beautiful ruins deep in the Pennsylvania woods are thought to have been a ski lodge or a speakeasy, but no one really knows.

A stone arch leads to a cavernous 1930s spring house tucked away in the Pennsylvania woods.

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

Mysterious rocks that ring musically when struck.

A toxic ghost town sitting atop a massive coal fire.

The real-life site of Ichabod Crane's infamous gourd attack.

An allegedly cursed tree represents a town's reckoning with a racist past.

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

An abandoned quicksilver mining town surrounded by the Big Bend parks.

An abandoned Jazz Age dream home and con man's hideout in Death Valley.

Abandoned 19th century homes once occupied by naval officers, soon to be demolished.

Ten 25-foot-tall, beehive-shaped kilns, abandoned in Death Valley.

Abandoned Air Force base that has fallen into disrepair.

Odd outsider art installations surround a Gold Rush-era ghost town.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

Abandoned power station once home to a squatter community, now being developed into an arts center.

A ruined mansion hidden in the woods of the Hudson Valley, home of a tragically doomed romance.

Beneath the mossy overgrowth covering this once-sprawling campus lies decades of history and the secrets that come with it.

A strange house built only at night, with rumored mystic inspiration.

The most unloved grain elevator in Brooklyn was a “Magnificent Mistake.”

A formerly abandoned mental institute, now back in business.

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

From scholastic to sepulchral - now under reconstruction.