A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

One of the largest artillery pieces in the world sits in a Washington D.C. parking lot.

Part of a WWII submarine is lurking outside the Washington Navy Yard parking lot.

One of the most influential presidents in U.S. history wanted only this plain, elegant monument as his lasting memorial.

Washington's iconic carousel has a nice piece of Civil Rights history.

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

The "lovely red Vega" of the legendary record-settling pilot.

Perhaps the most scandalous statue of America's first president.

The monument's pointy aluminum tip has been melted down by repeated lightning strikes.

Decades before the scandal, this staircase on the river was a literal "water gate."

The national park was once a plantation estate.

Rumor has it the hot dog stand was targeted by two Russian nuclear missiles.

This stately building in Alexandria, Virginia was built by Freemasons to honor one of their most famous members.

The U.S. Army's giant warehouse of war art includes Hitler’s watercolors and Norman Rockwell oil paintings.

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

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.

The romance of early commercial flight still fills this Art Deco destination.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

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

America's first federal monument.

A former major munitions plant that has been converted into a sprawling art space.

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