Vienna is a town in Fairfax County, Virginia, United States. As of the 2020 U.S. census, Vienna has a population of 16,473. Significantly more people live in ZIP codes with the Vienna postal addresses, bordered approximately by Interstate 66 on the south, Interstate 495 on the east, Route 7 to the north, and Hunter Mill Road to the west, than in the to…Vienna is a town in Fairfax County, Virginia, United States. As of the 2020 U.S. census, Vienna has a population of 16,473. Significantly more people live in ZIP codes with the Vienna postal addresses, bordered approximately by Interstate 66 on the south, Interstate 495 on the east, Route 7 to the north, and Hunter Mill Road to the west, than in the town itself.