A graveyard that dates back over 200 years stands near a busy shopping center.

This grave marks the passing of a historic Jane Doe whose identity remains a mystery to this day.

Government testing at the asylum briefly explored using marijuana as a "truth serum" on Nazi prisoners of war.

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

The rogue roots are gradually consuming some of the historic marble grave markers.

The United States Capitol's former columns still stand.

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

It was once the base for a series of domestic terror attacks.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

The national park was once a plantation estate.

The house where John Wilkes Booth conspired with his co-conspirators.

There's an old indoor swimming pool hidden directly underneath the White House Press Briefing Room.

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

Was there a small "backpack nuke" hidden in the attic? JFK apparently thought so.

A memorial to a shareholder activist feared by CEOs around the United States.

FDR's Art Deco hospital tower was hopelessly inefficient.

The wooded estate of the Forest Service employee responsible for D.C.’s cherry blossom trees.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.

A relic of FDR's brief foray into utopian urban planning.

This former asylum for Black Americans is haunted by its history of violence and racism.

Remnants of a storybook amusement park hidden behind a strip mall.