Mike, this was done at every major aircraft factory in Los Angeles during WWII.
LA was a huge source of airplanes built for the Allies during that time. Manufacturers included Douglas, North American, Northrop, and Lockheed. Right after Pearl Harbor was attacked, there was a huge fear of attack or invasion of the West Coast of the USA by Japan. Since Hollywood was so close by, their modeling departments were enlisted to create very real looking subdivisions on the roofs of these factories.
Very good work, IMHO.
