My cat just loves the Cat Tree house I purchased through Wayfair.   I was concerned that it wasn't going to be of good quality as the tree houses in the brick and mortar stores are so much more expensive, but we were pleasantly surprised of how well it was made.   All we had to do is attach the top bed to it, very simple.   It is very sturdy and of quality workmanship, and most importantly my cat just loves it.