I took this picture last Tuesday a few seconds after my airplane to Florida took off from the National Airport. Compare it with the map below.
Map is from TopoZone. I turned it around to align it with the photograph; the red arrow points to North.
The map identifies the flat light-colored building behind the Pentagon as the Navy Annex. The park to the right is the Arlington National Cemetery. The docked boats below the wing are in what is labeled in the map as the Lagoon, which is connected to the Potomac River just beyond the range of the map. If I had been sitting on the right side of the plane, I would have photographed the river instead.