The original Trachte plant was on the east side of Madison around the Dickinson-Mifflin-E.Dayton blocks. Many or most of the buildings (Trachte buildings, of course) are still standing, though the one at the corner of Dickinson and E. Mifflin caved in a few years ago and was removed.
Lots of pictures, as well as the difference between Quonset huts and Trachte buildings:http://www.madisonpreservation.org/gall ... s-company/
You'll recognize a surprising number of the buildings pictured there.
I think Mullins owns the old factory property now. It's a beautiful hillside on the edge of the Yahara River and I'd love to see it developed for residential purposes -- it's got no busy-street frontage at all. I suppose I might as well wait for hell to freeze over.