This is an office building for the famous farm-machinery company on a wooded tableland site crossed with ravines. The eight-storey administration building sits across the floor of the valley, a bit like a dam, with flying bridges either side leading to other buildings, laboratories and exhibition spaces, up the ravine sides.
I've always thought of Saarinen as one of the great twentieth-century architects. At the Deere headquarters he took steel to the ultimate. He said: 'Having decided to use steel, we wanted to make a building which was really a steel building,' rather than a glass building with steel supports. He chose CorTen, the rusting steel which ended up 'a cinnamon- brown colour which makes a beautiful surface on the steel'.
Saarinen had decided against curtains and venetian blinds, not least because they obscured the views. He worked out a system of reflective glass and sun shading using metal louvres which cut out 90 per cent of the sunlight.
The structure consists of an external steel frame on the outer layer, then the horizontal sun-shading grilles, then the vertical face of the building and then the steel and glass skin all in shadow. It's an entirely explicit structure; it belongs to that ancient Greek, post-and-lintel, Abbe Laugier, primitive hut tradition using sections straight out of the mill. And the sun screens are suspended on straps, it's real Meccano stuff. Or even more like using a bunch of old rusting railway rails and nailing them together. It's almost crude - tremendously vigorous. Saarinen wrote that farm machinery wasn't slick and shiny but 'forged iron and steel in big forceful, functional shapes'. And so the building had to represent that.
It's an architecture which has come from the nature of the material. CorTen has that special additional quality of not needing a protective coating. It develops its own. So here is a building for an agricultural company made from a material which, like agricultural raw materials, you dig up and process and use straight from the mill and then wait a couple of years while it sheds bits of its skin and finally settles down. It's like making, perhaps ironically, a building out of what the client does.
It must look wonderful, sitting there cinnamon-brown in the winter snow.