The Cradle of Humankind is a paleoanthropological site that is located about 50Â km (31Â mi) northwest of Johannesburg, South Africa, in the Gauteng province. Declared a World Heritage Site by UNESCO in 1999, the site is home to the largest known concentration of human ancestral remains anywhere in the world. The site currently occupies 47,000 hectares (120,000 acres) and contains a complex system of limestone caves. The registered name of the site in the list of World Heritage Sites is Fossil Hominid Sites of South Africa.
According to the South African Journal of Science, Bolt's Farm is the place where the earliest primates were discovered. Bolt's Farm was heavily mined for speleothem (calcium carbonate from stalagmites, stalactites, and flowstones) in the terminal nineteenth and early twentieth centuries.