The historic corbelled houses in the Northern Cape, South Africa, are excellent examples of the ingenuity of the early pioneers who moved into the Karoo semi-desert landscape from about 1820 through to the end of the nineteenth century. They discovered that trees were sparse and set about building their dwellings using the only available material, stone. As there could be no wooden trusses to support the roof, they made use of an ancient method of construction known as corbelling. This technique was implemented by placing successive courses of flat stone, each one extending a little further inward than the layer beneath, until the walls almost met at the apex. The remaining hole over the roof could then be closed with a single slab. 
