The resting place of a Civil War celebrity's amputated limb.

Outsider art meets paleontology at this roadside reptile repository.

Built by the patriotic residents of Boonsboro in a single day.

A Civil War Museum with some notable medical antiques.

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

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

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

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

The national park was once a plantation estate.

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

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

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

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

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

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

A computer bug so primitive it was an actual insect.

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

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

A historic ruin just 20 feet away from a busy highway onramp.

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.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

Home to items never before seen by the public.

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

Fittingly, America's museum of architecture is itself a magnificently designed old building.