Sandwiched inbetween the rail lines east of Kinnickinnik and the Milwaukee and KK rivers is a long-abandoned industrial site, with the remains of a number of buildings crumbling away among weeds and broken concrete. A bit of online searching reveals that this is the remains of the Solvay Coke Plant, which operated on the site from around the turn of the century until 1983 when it was abandoned. The coke manufacturing process is intensely toxic and left the site a contaminated brownfield.
Several intrepid explorers have published photos of this fascinating complex of buildings, including an especially good one here. Most of the site has been demolished in the last couple of years, a massive blank slate awaiting cleanup and redevelopment.
Photos from when the plant was in operation.
Development plans, from the Journal-Sentinel.