Here are some cool locations, some you can go inside really easy.
Jackson: North Construction Company
Lefere Forge
Goodyear Tire Plant (1504 Page Ave.)
762 East Washington Ave.
Cal-Air
Michner Plating Co. (Angling Road)
Michner Plating Co. (Mechanic St)
Ann Arbor: NA Publishing Co. (300 Zeeb Rd.)
Ypsilanti: Visteon Ypsilanti Plant