Haloedrain, thanks.  You're definitely right about the walls around the pools, I'll try to do something about that next.  I guess it didn't help that I've knocked this idea around over several months slowly evolving it so things have ended up changing their roles.

I know what you mean about the decoration but I'm deliberately trying to keep it plain on the outside if I can (I'm thinking in the direction of Hiagh Sofia in Istanbul for the main building).