I bought this because it is lightweight and modular, and therefore it can fit into a variety of spaces. The cats were sitting in the lower level before I'd even completed the construction. It was really easy to customize the build to get a design that worked in the corner space I had designated for it.  I also added some of their dangling wand toys to the posts, for more playing options. I would recommend putting pads into the hanging cubes to give them a more stable feel. I used the removable pads from two cat beds that are rarely slept in, to great success. It made the Kitty City smell like "home" which may be a part of why they took to it so quickly.  My cats are 9 lbs. and 13 lbs. and both fit on this comfortably. It is surprisingly more stable than it seems.