I mixed up the base and the second level as they look very similar and then had to take some of it apart and redo. If you buy this make sure that the go pet club logo is on the bottom. Other than that it was very simple to put together and pretty sturdy. My 16 yo Roxy doesn’t like it very much but my 1 yo loves sleeping on the very top and playing with the mouse. I’ve had it set up for a few weeks now and so far so good