Brentsville Courthouse served as the fourth courthouse for Prince William County. For seventy years, county business, including trials, paying taxes, and voting, took place in the building and on its steps. Auctions were also held there, including the buying and selling of slaves. After the county seat moved to Manassas in 1893, the courthouse was converted into the Prince William Academy from 1897 to 1909. The building was then used as a community center and office space until it was restored and opened to the public as a museum in 2007.