We have a big cat...almost 18lbs. and we wanted something sturdy enough for him to enjoy.  The cat tree is perfect.  He loves it. The large shelf near the top is large enough for him to lay on and he sleeps there most days.  The openings on the enclosures allow him to get into them with his head out one end and his tail out the other...but he does get into them and likes to play in and out of the enclosures.  We have been delighted with his response his new "tree".  He loves it and we enjoy watching him play on it and sleep on it.  He is happy and we are very pleased.,  Thank you.