This is a large tub, but allowing for a dragon or two,

should be about right. Covered and connected to some of the solar panels on ramparts it should stay nicely warm, and heat up fast when uncovered for use.

Will need to coordinate plans with Reb's builders and see if we can incorporate telescopes on mounts around the side so they don't be falling in the water.  Also some ledges for wine bottles and glasses sensible drink containers!