This site currently occupies 47,000 hectares ( 180 sq mi ) ; it contains a complex of limestone caves , including the Sterkfontein Caves , where the 2.3-million year-old fossil Australopithecus africanus ( nicknamed `` Mrs. Ples '' ) was found in 1947 by Dr. Robert Broom and John T. Robinson .
A 2.3-million year-old fossil Australopithecus africanus ( nicknamed ` Mrs. Ples ' ) was found in 1947 by Robert Broom and John T. Robinson .