The only U.S. Senator to die on the field of battle is buried in San Francisco but memorialized at Balls Bluff Regional Park.

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

The last of Fairfax County's one-room schoolhouses.

A secret rendezvous spot where John S. Mosby and his Rangers would meet to divvy up their loot after raids.

This restored house built from a Sears kit in the 1930s is a physical remnant of FDR's New Deal following the Great Depression.

Named for a Greek oracle that interpreted the words of Zeus, this beautifully-restored manor home was once home to the architect of the Marshall Plan.

The all-but-forgotten cemetery is Eastern Loudon County's largest African-American burial ground.

A massive white oak tree provides a beautiful canopy near a suburban shopping center and stood before the signing of the Constitution.

Once the center of a thriving early Black community called Martinsburg.

This general store has stood in the same spot for well over a century.

The only public school for Black children in the region from 1895-1936.

Dating to 1793, this is the oldest building in Poolesville.

This suburban park recalls the history of a famous tavern. Despite the name, it's no ordinary place!

The hidden ruins of a mill that is linked to an attempt to assassinate the vice president of the United States.

A well-worn trail through thick woods in northern Montgomery County leads to an old schoolhouse.

The ruins of an old mill lie in a small ravine along a hiking trail near Little Seneca Creek.

Using a massive antenna made up of five miles of wire, two scientists tuned into organic radio waves from the planet Jupiter.

Built in 1815, the stabilized ruins of the grist mill and sawmill are now gated, but interpretive displays on the features and functions of the mill preserve its history.

Built in 1945, this historic train station has a new lease on life with its baggage area serving as an event space.

This bell is one of the last remnants of the lost city of Triadelphia.

This marker at the entrance to the Humphreys Engineer Center honors the former Chief of the Army Corps of Engineers.

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 mighty white oak in Bethesda survived both the American Revolution and the construction of Washington D.C.'s metro red line.

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