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

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

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

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

This abandoned ironworks was once the most important military supplier in America.

According to the experts at the Guinness World's Record office, this is the longest candy counter in the world.

The sweetest graveyard in the world is filled with headstones for dearly de-pinted ice cream flavors.

The oldest continuously inhabited street in America.

This once-private estate is now a dreamy, meditative garden that's open to the public.

This mouldering abandoned mental hospital was once a center for progressive healing.

Remnants of a wall built to separate Black residents of Hall's Hill from a newly built subdivision are a grim reminder of segregation in 20th-century Virginia.

This eye-catching sculpture of rural life seems a bit out of place at a suburban intersection in front of a car dealership.

This train station inspired the name of a 1970's rock band and provided the backdrop for their album cover.

The former home of Thomson Francis Mason, the mayor of Alexandria from 1827-1830.

This "castle" is actually a limestone and quartz formation hidden along a trail.

Originally dubbed "Retirement" by the Navy Commodore who built it in 1780, this beautiful mansion is now the centerpiece of a suburban community park.

Built to defend Washington D.C. during the Civil War, this fort became a post-war nucleus for a thriving Black community.

Hidden in the forest atop a long, winding driveway is this stately home.

The only surviving 19th-century water-powered mill found in the Washington, D.C. area.

Get up close and personal at this Fresnel Lens.

Long buried under the 20th-century landscape, this lift lock of the Alexandria Canal is the lone remnant of an ambitious early American transportation project.

This homestead was occupied by Union soldiers, who believed the owners were signaling Confederate forces.

This church built atop a gas station promises to "equip you for the next stage in your life’s journey."

The last of nine massive kilns that produced many of the red bricks for buildings in Washington, D.C. and northern Virginia in the early 20th century.