<Li> <P> Siemens office building in Munich - Giesing </P> </Li> <P> Siemens office building in Munich - Giesing </P> <Li> <P> Siemens - Tower in Berlin - Siemensstadt </P> </Li> <P> Siemens - Tower in Berlin - Siemensstadt </P>

Who owned the largest manufacturing operation in the 1920s