Merc, there are steel welded homes in Troy OH...built by Hobart Bros back in the day. Sometimes you can pick them out, knowing what neighborhoods they're in, but often it's hard to tell. I was in one once. They had a hard time keeping the rust off the walls from moisture. Here's an article about one of the nicer ones (I"ve always found them interesting, and try to spot them when I am in that area.)
http://www.waymarking.com/waymarks/WM410B