This Mighty Cat Tower is unusual in that it wraps around a corner with an unusual footprint to make it less obtrusive. What a great idea! You probably should anchor it to the wall, but if the base is heavy enough maybe it wouldn’t need it.
The post is short on instructions, but has a good list of materials. And there’s a video to teach your kitties how to make the most of their cat tower. Check out previous posts on building:
Important Note: the author of on of the Cat Tree tutorial recommends using 3/8″ Brazilian sisal rope because it’s stronger, but more importantly because it’s less heavily oiled than other sisal rope.