The Ngorongoro Conservation Area is a protected area and a UNESCO World Heritage Site located in Ngorongoro Distric, 180 km (110 mi) west of Arusha City in Arusha Region, within the Crater Highlands geological area of northern Tanzania. The area is named after Ngorongoro Crater, a large volcanic caldera within the area. The main feature of the Ngorongoro Conservation Authority is the Ngorongoro Crater, the world's largest inactive, intact and unfilled volcanic caldera.[18] The crater, which formed when a large volcano exploded and collapsed on itself two to three million years ago, is 610 metres (2,000 feet) deep and its floor covers 260 square kilometres (100 square miles)
