America's first federal monument.

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

This small pedestal marks the spot of the first lot of land sold in Alexandria, Virginia in 1749.

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.

A derelict bit of transportation infrastructure hidden in the woods.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

Home to items never before seen by the public.

This ruined quarry once produced the distinctive red sandstone used for construction projects in Washington, D.C.

The rooster who crossed the road lives on forever in Takoma Park, Maryland.

Live data is transmitted from the Atlantic coast to instantly recreate the ocean waves in this fountain at the NOAA headquarters.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

A line of blue paint marks the route of the inaugural parade.