The Ngorongoro Conservation Area (809,440 ha) spans vast expanses of highland plains, savanna, savanna woodlands and forests, from the plains of the Serengeti National Park in the north-west, to the eastern arm of the Great Rift Valley. The area was established in 1959 as a multiple land use area, with wildlife coexisting with semi-nomadic Maasai pastoralists practising traditional livestock grazing. It includes the spectacular Ngorongoro Crater, the world’s largest caldera, and Olduvai Gorge, a 14km long deep ravine. The property has global importance for biodiversity conservation in view of the presence of globally threatened species such as the black Rhino, the density of wildlife inhabiting the Ngorongoro Crater and surrounding areas throughout the year, and the annual migration of wildebeest, zebra, Thompson’s and Grant’s gazelles and other ungulates into the northern plains.