It seems to stretch onto blocks on both sides of Brown Avenue and terminates on the west side of Geraldine Avenue.
The Sanborn Map from 1920 shows just how massive the plant was, and how we can see what each of the buildings had a different function. The brown color is reinforced concrete, illustrating improved construction and safety building practices.
This aerial photograph from the 1930s also shows why they moved out here: lots of wide open space. I often hear criticism of major corporations moving out to the suburbs in the post-World War II era, but in reality, it was often for practical reasons.
New manufacturing practices, whether for massive new automobile assembly lines or whatnot, required huge swaths of open land, and as we can see was already happening in the first decades of the Twentieth Century in the City of St. Louis, factory owners needed more room that crowded neighborhoods in the heart of the region could not provide.
As mentioned before, judging from the architectural, the buildings south of Brown seem to also be part of the complex.
These clearly seem to be loading docks; while there are excellent rail connections, note how much space is given to truck access (the garage doors have been bricked up). The Twentieth Century was definitely here with its increased emphasis on the automobile.
I wonder if those roundels once held the company’s logo.