On my family's list of places to visit that are supposedly super haunted, one I recently read a bit about is Jerome, Arizona. From stuff I've read, in the old days it was a big copper mine before declining. So many people died in the mines (and giving even a single shit about your employees wasn't a thing yet) that they started cremating them in the blast furnaces. The town also had a habit of burning down, so at one point they decided to use the slag from said furnaces, full of dead people, to make concrete for buildings and sidewalks. That and some of the old buildings look neat.