I was apprehensive about ordering a cat tree that I'd have to assemble -- I've not had the best track record with assembly. But this was truly so, so very easy to assemble. I separated all the parts by the lettering described in the enclosed instructions and it only took 25 minutes to complete!! Amazing!! The base is big enough to support the upper structure and is very stable. It does wobble ever so slightly but I think that's because I have it on a carpeted floor. Admittedly, I didn't add the very top level on the structure..not because I thought it would make it less stable. Rather, the sisel post would have to be attached to the top of the "house" and would leave less room for kitties to curl up and sleep. It looks great in the living room and its very easy to clean. And most importantly, both my cats absolutely love, love, love it!! Thank you for yet another really great product! I'd totally recommend this product.