When we moved to our new apartment/condo, our children became indoor cats. In the past they were free-range, but they spent almost all of their time inside.
Since we moved, it's been my job to find them a cat-tree/platform to play/sleep on and watch the world outside from. I have to consider that Che can't comfortably jump higher than 18" at a time. And we want a platform that Che and Jawa can share.
The Lotus at $300 is not cheap, but it is the most suitable cat-tree I've found.