Austin,_Texas | isPartOf | Hays_County,_Texas Williamson_County,_Texas | largestCity | Round_Rock,_Texas Austin,_Texas | isPartOf | Williamson_County,_Texas Williamson_County,_Texas | countySeat | Georgetown,_Texas
Austin, part of Williamson County, is in Hays County, Texas, where the largest city is Round Rock. Georgetown is the county seat of Williamson County, Texas.