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.

These abandoned waterworks are crumbling into the Potomac River.

A historic cemetery with unique artwork, a Civil War fort, and also happens to be the site of the Battle of Bladensburg.

A Civil War fort in the middle of Washington, D.C. has been swallowed by a forest.

Washington's top-secret Cold War-era doomsday communications tower is located in a small neighborhood park.

The remains of a historic plantation nestled in between a parking lot and the rental car return at Reagan National Airport.

The only Civil War battle in Washington D.C. took place near this highest natural point in the city.

Once the supplier for noteworthy projects like the National Cathedral, this old brickworks now lies abandoned.

The United States Capitol's former columns still stand.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

A rare example of a rural school in Washington, D.C.

The Conduit Road Schoolhouse is one of the last one-room schoolhouses remaining in Washington, D.C.

This forgotten boat elevator was an engineering marvel in its heyday.

This site is believed to be connected to the oldest house in Arlington County.

Cold War intelligence agents monitored communist embassies from an attic in a former pigeon coop.

100 years later, they're still down there.

A derelict bit of transportation infrastructure hidden in the woods.

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

Once a sewer culvert, this road tunnel now offers cyclists and pedestrians a subterranean stroll under the C&O Canal.

There's a crumbling old mansion inside the Smithsonian National Zoo.

Before Nixon, "watergate" meant canals.

A historic ruin just 20 feet away from a busy highway onramp.

People escaping slavery may have hidden inside a corpse vault.

The former home of elite checkers battles of the Capital Pool Checkers Club.