Brentsville Courthouse and Jail is a historic courthouse and jail located at Brentsville, Prince William County, Virginia. The courthouse was built in 1822, and is a two-story, Federal style brick building. It features a fanlight over the main entrance, within a keyed, semicircular brick arch and an octagonal-roofed, frame-built cupola. The Brentsville Jail was built about 1820, and is located 30 yards from the courthouse. It is a well-constructed, two-story, gable roofed structure. The county seat was moved to Manassas in the 1890s to the Prince William County Courthouse and the courthouse and jail were abandoned.