Fairfax County, Virginia was established on May 6, 1782 and named after Lord Thomas Fairfax of Cameron, who was proprietor of the Northern Neck peninsula on Chesapeake Bay! Its county seat is Fairfax, and its fair is held in Herndon! You might recognize Mount Vernon, Wolf Trap National Park for the Performing Arts, Manassas National Battlefield Park, and Great Falls Park, which are located in this county!