Town Hall Address 221 East Main St. Round Rock, TX 78664 United States- Williamson County Website https://www.roundrocktexas.gov Zoning 512-218-5428 301 W. Bagdad Ave., Suite 210 Round Rock, TX 78664 United States Town Clerk 512-218-5400 221 East Main St. Round Rock, TX 78664 United States Tax Collector 512-218-5400 221 East Main St. Round Rock, TX 78664 United States County Williamson