During the Second World War, the Thorp building, today located in the heart of the Northeast Minneapolis Arts District, was taken over for wartime production. The General Mills Mechanical Division used the building to produce the now-famous Norden Bombsight, which was, at the time, the best precision bombing device in the world.

The production of this secret weapon was so important to the Allied war effort, the security of the project rivaled that of the Manhattan Project in New York, involving the OSS, the FBI, and the US Navy.

The Thorp building has now been subdivided into a lot of smaller units, including many artists and artisans. But outside the building, two of the four US Navy Guard towers from this clandestine wartime operation still stand, a remnant of the days when it was considered one of the most secret and best-guarded buildings in the country.

All this security was, however, somewhat too late. The details of the bombsight had been passed to the Germans by Norden employee—and German spy—Herman W. Lang in 1941.