I wanted something I could leave on my back porch for my kitty to enjoy when outside, so I bought this with the Starter Kit Cat Perch.  It goes together like Tinker Toys and is made of plastic tubes, nylon and washable panels, and it's easy to put together and take apart.  He seems happy with it and was in the sleeper part before I had the whole thing built!  You can configure it any way- I put the sleeper condo on top of the Starter Kit with the green cube on the bottom giving him a 3 section middle part to walk across and lounge on.  Wayfair.com beat everyone else's price on all the Kitty City stuff, too.