Fairfax, Virginia, formally the City of Fairfax, and colloquially known as Fairfax City, Downtown Fairfax, Old Town Fairfax, Fairfax Courthous…Fairfax, Virginia, formally the City of Fairfax, and colloquially known as Fairfax City, Downtown Fairfax, Old Town Fairfax, Fairfax Courthouse, FFX, and Fairfax, is an independent city in Virginia and the county seat of Fairfax County, Virginia, in the United States. As of the 2020 census, the population was 24,146.