Very stable and sturdy design.  I have two large 15lbs cats who run up and down the tree constantly. It’s nice to not worry about it falling over.  One time my friend’s 2 year old tried to shake the tower so she could get the cat down from the top tier of the tree, it barely moved. The cat woke up with an annoying stare, down to the kid, and then fell right back to sleep.  Definitely would recommend.  One tip though: When you get all the parts out to build the tower, sort all the different lengths of “post” pieces by order of size, and put a note near each one with the corresponding letter written on it.   There isn’t any Letters or stickers on the parts which was only a minor inconvenience. With the exception of the similar looking posts, all of the other parts are easy to identify as the picture diagram is very clear and easy to follow.