Some of the wackiest houses I encounter are built in the desert. Something about no neighbors close by and plenty of room to roam lets the imagination take flight. Case in point, Casa Mariposa, the Butterfly House, in Fountain Hills, Arizona is a 18,595-square foot main home with four bedrooms, a 70 x 40-foot great room, two elevators, a library, study, billiard room and two garages with room for 10 to 15 cars and a maintenance pit. The home is on 3.4 acres and has a grotto, pool-sized waterfall and nearly as much outdoor square footage in the pavers as the house itself. The butterfly theme is reflected in the marble floor, the doors and even some of the windows. This estate is listed at $9 million.