martians, lumerians. land grants. >>> walking private ranch land with swanson.hard not to get caught up in this mystery. >> if you see this thing, it's collapsed a bit. but you can see it's a middle shape. >> it may have been built 200 years ago or earlier no one knows. this circle of stone feels old. >> it could have been a watchtower or hunting if blind. >> who's went to all this enormous work to put these things together? >> naturalists say a massive construction project like this could only have been done during or after