Uninhabited Sheds

There are some strange marks on the russian and soviet topographical maps - "Uninhabited Sheds". What does it mean? You can make a long and hard trip in the wild places and forbidden zones, you are hiding away from sequrity or frontier-guards, you are steal through rain, snow or mosquitos, hungry as a hunter to that mysterious "Uninhabited Sheds" (Sarai neziloj). And what do you find? The deserted rocket shaft for example... The same thing is on the picture. It is standing near the road to Priozersk city. I have seen it many times and did not know - what is it...