The former home of the man whose radical ideas changed the nation.

The tomb was guarded by soldiers from both sides of the war, and some left their initials carved in the brick.

This simple stone memorial remembers a secret, Geneva Convention-defying interrogation base from WWII.

Remains of a historic fountain that was mysteriously lost in the demolition of a D.C. traffic circle.

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

A mammoth pair of Civil War artillery guns abandoned out in the forest.

The 72-foot giant escaped confinement in a large patch of mulch only to be reburied in the sandy shores of the Potomac River.

This rare triple-jurisdiction drawbridge passes through Virginia, Maryland, and Washington, D.C.

This cannon dating to 1755 has stood guard at this suburban intersection since 1915.

This brick-lined pedestrian walkway was once a railway tunnel used during the Civil War.

A massive, majestic mammal watches over pedestrians from his perch atop a former B.P.O.E. lodge.

An original apothecary from 1792.

A superbly preserved example of Georgian residential architecture that was once home to one of the founders of Alexandria, Virginia.

This colonial tavern played host to George Washington, Thomas Jefferson, and other famous early Americans.

The narrowest house in America is seven feet of pure spite.

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 lovely picnic spot featuring thunderous jet landings is an aircraft spotter’s dream.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

These recently uncovered walls are all that's left of Washington, D.C's first defense contractor.

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

The national park was once a plantation estate.

At 207 feet, one of the world's longest continuous escalators.

The only thing better than tubing down New Jersey's scenic Delaware River is doing so while eating a hot dog from a giant floating stand.