Melville Koppies is a Nature Reserve and a Johannesburg City Heritage Site. It is the last conserved remnant of Johannesburg’s ridges as they were before the discovery of gold in 1886. Its geology goes back three billion years. Stone tools show that Early Stone Age man camped here as long as 500 000 years ago. There is a Late Stone Age living floor. Within the last 1 000 years Iron Age immigrants arrived, and remains of their kraal walls can be found on the northern slopes. In 1963 an iron-smelting furnace was excavated and can be seen today.