Who Knows? Ancient Buildings/MonoMonday

I have no idea. It's certainly not an ancient building. It's likely not even a building in any real sense - more of a structure. It was behind a house that is no longer there, having been torn down a number of years ago. There is a falling down bench; what appears to be an old mailbox lying on the bench; and the structure, whatever it might be. It's at the point in our regular walk where the husband and I turn around and head back. "Nellie's house" that was - Nellie being someone we used to buy eggs from back when we were first married 40+ years ago. She is dead and her house is gone and this is all that remains. Maybe it's a well house or something? Why else leave it standing? The property is now owned by the woman across the street who has the horse farm where Quentin and Coralee live. They have appeared in at least one previous blip of mine...

Thanks to JoanneInOz for hosting!