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

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

The site of the climactic scene from the classic horror film is now a historic landmark.

The most decorated dog of World War I is preserved in the Smithsonian.

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

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 grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

Look closely and you’ll notice that the color changes a third of the way up the tower.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

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

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

Home to items never before seen by the public.

This lovely pocket park is one of the most under appreciated in D.C.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

At 207 feet, one of the world's longest continuous escalators.

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.

A small and somewhat hidden memorial to 68 local veterans of the Vietnam War.

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

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

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

This colonial tavern played host to George Washington, Thomas Jefferson, and other famous early Americans.

The final resting place of an unidentified revolutionary soldier sits behind a Virginia church.