How to build a cat tree

Someone needs to build a cat tree for kitty so kitty doesn't get bored and has a place to go away from those stupid dogs. Here is a great DIY on building a cat tree
Here are some tips from dollar stretcher.com, I like the ladder idea, makes for re-using a ladder with jute rope between the legs, and of course we wouldn't be proper without an instruction from Martha Stewart on how to build a condo from a tree branch.