The slates you see inside appear to be adjustable maybe ? I have not taken the time to research it at all but when I looked at it I thought it might be a Drag line ....or something to do with mining....or something like that. Husband thought so to. It is metal and big. You can I think see the size from the chain link fence it is in front of.
I think the kids are going to put Christmas light on it..Whatever it is.