I like to take pictures from airplane windows and then try to identify the landmarks in the pictures using Google Earth. I took this one last month on our way back from Florida as we were approaching the Washington National Airport from the south flying right above the Potomac River. The picture shows the eastern (Maryland) side of the Potomac.
I had no idea how far from the airport we were when I took the picture and because of that I wasn't too hopeful about locating the place in Google Earth. But, to my surprise, I found it quickly.
Picture from Google Earth. Turned 90° left to match its orientation with my photo ( North is to the left).
It looks like some sort of water treatment facility or sewer plant located off of Route 210 between Accokeek and Fort Washington. Maybe someone familiar with that area will eventually enlighten us as to the identity of the place.
Picture from Google Maps.
The picture from high above No. 7 was wind turbines in New York.