Ngorongoro Crater

The Ngorongoro Crater is the world's largest intact -- and inactive -- caldera in the world. Formed more than two million years ago from a huge volcanic explosion, the Crater is now a UNESCO World Heritage site teeming with wildlife. Visitors can see more than 25,000 animals, including four of the Big Five. It's home to the biggest population of Masai lions in Africa and is where wildebeest come to calve during the great migration.