Central Texas is a region in the U.S. state of Texas surrounding Austin and roughly bordered by San Saba to Bryan and San Marcos to Hillsboro. Central Texas overlaps with and includes part of the Texas Hill Country Central Texas includes the Austin–Round Rock, Killeen-Temple-Fort Hood, Bryan–College Station, and Waco metropolitan areas. The Austin–Round Rock and Killeen-Temple-Fort Hood areas are among the fastest-growing metropolitan areas in the state. Some of the largest cities in the region are Austin, College Station, Killeen, Round Rock, and Waco. The largest U.S. Army installation in the country, Fort Hood, is located near Killeen.