This is a great size and it was very easy to assemble. I usually leave assembly to my husband and this time I attempted it on my own. There were no written instructions. Only one picture with arrows showing how it all goes together. So, if this girl, who cannot usually follow illustrated directions was able to put it together on her own then  most anyone can (although I did have to take it apart once because I forgot to consider lining up the cat entries so they were on the same side. Maybe that should have been highlighted in the picture.) Cats love it. Seems sturdy. Perfect window height for bird-watching.