lies 75 miles (120 km) west of the town of Arusha. The caldera measures between 10 and 12 miles (16 and 19 km) across and has an area of 102 square miles (264 square km). Its heavily forested rim rises 2,000 feet (610 metres) above the caldera’s floor to an elevation of 7,500 feet (2,286 metres). Ngorongoro is thought to have formed about 2.5 million years ago from a large active volcano whose cone collapsed inward after a major eruption, leaving the present vast, unbroken caldera as its chief remnant.
Large numbers of tourists began visiting the caldera in the 1930s, when a lodge was built on its rim. Since the region’s incorporation into the Ngorongoro Conservation Area in 1959, additional lodges have been built. The caldera is included within a UNESCO World Heritage site designated in 1979.