17. The Whispering Windmill Arboretum
A unique fusion of pastoral utility and treehouse living, this design features a large, working oak-and-wool windmill built onto the highest branch of a mega oak tree. The rotating sails, made from white wool and oak fences, turn slowly against the sky. The lower platforms surrounding the trunk feature small wheat and flower gardens, while the main interior of the windmill serves as a multi-floor home with a grain-grinding floor (utilizing grindstones and hay bales), a cozy kitchen, and a top-floor bedroom nestled right under the turning axle.