Austin,_Texas | isPartOf | Texas Texas | largestCity | Houston Austin,_Texas | isPartOf | Williamson_County,_Texas Williamson_County,_Texas | largestCity | Round_Rock,_Texas Williamson_County,_Texas | countySeat | Georgetown,_Texas
Austin Texas is part of Williamson County (county seat: Georgetown), whose largest city is Round Rock. Houston is the largest city in Texas.