The Vandalia State House, built in 1836, is the fourth capitol building of the U.S. state of Illinois. It is also the oldest capitol building in Illinois to survive, as the first, second, and third capitol buildings have all disappeared. The brick Federal style state house has been operated by the state of Illinois as a monument of Illinois' pioneer years since 1933. It is located in Vandalia, Illinois, on the National Road (and National Old Trails Road), and listed on the National Register of Historic Places.