These folks (who wish to remain anonymous) rescue kitties. They have built an amazing enclosure for them to keep them safe while still allowing them to explore outdoors. We added to that with a living pond that keeps the cats entertained for hours! See more: http://www.pondgnome.com/ponds.html

Read the great article that Houzz wrote about this project: https://www.houzz.com/ideabooks/20041678/list/see-a-deluxe-catio-built-for-feline-fun