Multi-cellular sheep fold

This has nothing to do with either the Ice Age or Stonehenge, but I was so impressed when I saw this that I had to share it.......

Castles and churches are all very well, but this is quite wonderful. A multi-cellular sheep fold in the mountains of North Wales, near Bethesda. When the sheep are taken in off the mountain, each farmer can drive his flock into his own particular cell for marking and sorting. A triumph of low-tech engineering and social cooperation....... from the RCAHMW web site.