In this central Tucson backyard, we used circles to concoct a curvaceous plan: we began with a cylindrical rainwater cistern, a circle of turf, a raised circular cacti and succulent bed, with an adjacent circle pattern pavers. Behind high colored walls in the corner of garden, we tucked in big circular wooden hot-tub. The garden, which is kept-up by a busy mom with a very green thumb and good design eye, also contains a veggie garden and pot shelves along the wall. The central cactus bed contains, fire barrel, white-stripe agave, and slipper plant.