THE CRADLE OF MAN: The Olduvai Gorge is a steep-sided ravine in the Great Rift Valley that stretches through eastern Africa. It is in the eastern Serengeti Plains in northern Tanzania and is about 48 km (30 mi) long. In 1959 the first bones of the very earliest forms of people were found here. It is now thought to be the “Cradle of Man” where it all started for us.