Fountain Hills is a town in Maricopa County, Arizona, United States. Known for its impressive fountain, once the tallest in the world, it borders on the Fort McDowell Yavapai Nation, Salt River Pima-Maricopa Indian Community, and Scottsdale, Arizona. The population is 22,489, as of the 2010 census. Between the 1990 and 2000 censuses it was the eighth fastest-growing place among cities and towns in Arizona.