The Alphen estate was granted to Theunis van Schalkwyk in 1714. Its historic homestead is a square plan double-storey manor house with a well proportioned pediment and a well designed front door, whose construction dates back to the mid-18th century, although the upper storey was probably a later addition. It was declared a National Monument under old NMC legislation on 30 June 1973. Nova Constantia, Constantia Valley. This originally formed part of the Groot Constantia estate, and the house probably dates from the first quarter of the 19th century. The homestead is based upon a U-plan and, because of its impressive gables and its setting, is widely considered to be one of the finest Cape Dutch houses. It was declared a National Monument under old NMC legislation on 12 October 1973.