Yeah, the first one you mention is just a tower. It's mostly intact. The bigger towers and one with the raised wooden floor are more the ones I wonder about. I'll rebuild them to my own specs if they're in a good spot but other than the walls, I'd still like to know what they were intended to look like. I actually knock out one of the walls on the bigger ones a build in a hearth. Usually it's the wall opposite the entryway on the medium sized stone buildings. Because of their usefulness, when I set sail to a new place I bring mats for a portal and two iron bars for the Stone Cutter.