A historic grist mill and active sluice on the Black River.

A recently abandoned psych ward at the end of Sanatorium Road.

Spies, love letters, and ghost stories have all left their mark on this home-cum-museum.

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

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

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

An isolated beacon with a history of grisly murder and a view of some of literature's greatest inspirations.

Forgotten under the construction of a new urban roadway is a small, abandoned part of town.

A trail weaves through the verses of a poem illustrated by stone sculptures inspired by Native American pictographs.

A long spiraling walkway winds through the woods, and around a copper beech tree at the center.

Astonishing collection of helmets, scientific instruments, and medical models.

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

Every winter, the wind carves blocks of frozen water into beautiful abstract shapes inside this unusually curved tunnel.

The menacing creature had a tremendous influence on the local culture before being exposed as a hoax.

A wooden theatre that remains the heart of a charming Victorian-era New Jersey enclave.

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

This Great Depression-era creation was once known as the strangest house in the world.

The site of one of history's most indelible and horrific tragedies.

A living antique aviation museum in the historic town of Red Hook, New York.

A CT scan revealed the identity of this 3,000-year-old mummy that everyone erroneously thought was female.

Manhattan's Thirteenth Avenue was made on landfill then deliberately destroyed — apart from one small, obscure block.

This small Catskills village has six independent bookstores and more bookshops than restaurants.

Final resting place for the Triangle Shirtwaist fire’s unidentified victims.

The first museum in the United States dedicated entirely to posters.