Fairfax, city (1990 pop. 19,622), historic seat of Fairfax co., NE Va., a residential suburb of Washington, D.C.; inc. 1892, as a city 1961 (at which time it became independent and no longer included in a county). There is some light manufacturing. In the old courthouse (built 1799; restored 1967) are the wills of George and Martha Washington. Both the county and the city have many historic structures, notably Gunston Hall (1755–58), Pohick Church (1774), and Sully Plantation (1794). George Mason Univ. is located in Fairfax.