High Quality Content by WIKIPEDIA articles! The Historic Fairfax County Courthouse is one of the oldest buildings in Fairfax, Virginia. It was constructed in 1799 to serve as the seat of government in Fairfax County. During the American Civil War, the first Confederate officer casualty of the war took place on the courthouse grounds, and the building was occupied by both sides in the conflict. Today, the original courthouse building is part of the larger courthouse site that serves the local government of Fairfax County.