The box was packed in a way that made it necessary to peel it like a banana to get the two pieces out.  Assembly was easy - a screw in the top piece (top level) goes into the hole in the bottom (two levels).  However it was frustrating because the threads took forever to catch and then the final piece is not level and makes the cat nervous.  Maybe he'll get up there eventually, after all, it took a week for him to trust this new furniture enough to master the middle level, but so far each time we show him the top he gets nervous as it seems to tip.  We'll just have to see!