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

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

A mammoth pair of Civil War artillery guns abandoned out in the forest.

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

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

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

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

The world's oldest continuously operating airport was founded by the Wright Brothers.

The tallest The Church of Jesus Christ of Latter-day Saints temple in the world soars above the Beltway.

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

FDR's Art Deco hospital tower was hopelessly inefficient.

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

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

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

The U.S. Navy’s preposterously detailed mini battleship took 77,000 hours to complete.

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

This lovely picnic spot featuring thunderous jet landings is an aircraft spotter’s dream.

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

A nostalgic bibliographic gem.

The naval commander’s proudest moment in battle is memorialized in this unique tomb at Arlington Cemetery.

Born a slave on the Arlington estate, Parks dug the first graves at Arlington National Cemetery, and was buried there, too.

Soldiers were buried next to Lee's house in the center of Arlington Cemetery to dissuade the general from reclaiming his property after the war.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.