On our first full day in Washington, D.C. during our late March 2024 trip, we walked to the Crystal City metro station, bought Smart Trip cards, and rode the yellow line to the L'Enfant Plaza station, which is an easy walk to the National Air & Space Museum. After touring the museum and having lunch there, we walked to the National Botanic Gardens, and then to the Capitol building. I didn't show it in the video, but we took a bus back the entire way we'd walked plus some, and got off at the National Archives, but the line to get in was very long and not moving.