I've only seen one cat run set up in real life. A guy who had 5 cats had made a cat run in his very large backyard. It had stations (very large cages) with cat trees in them in different areas so the cats go around the yard if the wanted and/or just sit on the perches and watch the birds. The cats stayed protected from other animals - he lived near a ravine so there were lots of raccoons etc. It was very impressive, and the cats seemed to love it. BUT it was also very expensive. I've heard of cat fences - netting that goes on the fence so that the cat can't climb out. Has anyone used either of these? What are your opinions of them? Thanks, Jeanette