B747-200 Window Frame - Air France - Le Bourget

Here we see a close up view of the window frame belonging to a B747-200 of Air France, now preserved at the Le Bourget Air and Space Museum just outside Paris.

I remember flying on B747's in the late 70's and the windows would often be difficult to look out of, because of a phenomenon called grazing where particles in the air would act like sand paper and over a period of years in service would slowly render the window opaque, as if somone had applied sand paper to it. Of course new processes and materials have been developed to eliminate this problem in recent years.