Along the Palisades skyline are the ruins of a large mansion built in 1911 and demolished in the 1930s.

Self-sufficient greenhouse floating on the Hudson River.

A beautiful, historic location open to the public.

This once-grand marvel of engineering is now 41 miles of scenic hiking trail.

This dilapidated castle-like structure overlooks the Hudson River at one of its widest points and was once home to nuns.

The first pet cemetery in the United States.

One of the earliest bowling lanes in the U.S. doubled as a sewing school during a time when women had little job opportunity.

This tiny church near Sleepy Hollow contains Henri Matisse's last work, a rose window, and nine windows by Marc Chagall.

This giant rock arrived at this quiet park thousands of years ago on the back of a massive glacier.

These World War I shooting range tunnels are now haunted halls of underground graffiti accessed through the roots of a tree.

A historic Black graveyard hidden in the parking lot of one of America's largest malls.

Reclaimed by nature, the ruins of Doodletown, New York are remnants of a town consumed by a state park.

This sprawling woodland estate was the brainchild of iconic American industrial designer Russel Wright.

Reforestation in action is the main attraction in this abandoned quarry.

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

Collapsing castle on the Hudson river was once the storage site of military surplus business.

The remains of what was once the world's steepest passenger funicular.

A 19th century hat factory still stands as a crumbling ruin in upstate New York.

The largest known open fault in the United States is basically a giant natural refrigerator.

This old cement mine has been used as everything from a mushroom farm to a recording studio.

"A hideous albatross in the Hudson River Valley."

What was once a trend-setting, phrase-coining icon of architectural splendor is now a rotting, forgotten hulk.

The life of one of FDR's possible mistresses is preserved in her palatial Hudson Valley mansion.

One man's swirling six-acre monument of stone.