Ngorogoro Crater

The  was an area within the Great Rift Valley of Africa. The Seventh Doctor took Ace there in March 1926. It was a natural habitat whose high walls prevented the animals within from ever crossing to the wide world outside. It was a natural habitat for lions, gazelles, buffalo and zebra, elephants and rhinos, amongst other large mammals.

On his March 1926 trip, the Doctor was reminded of another trip, in which he'd witnessed the shooting of the last lion on Earth. Ace, for her part, wasn initially unimpressed with the area, until a Maasai chief named Naikosiai took her on a personally-guided tour of the crater. She came away impressed not only by the large game animals but also the "hundreds and thousands of termite nests". (DWM: Prelude Birthright)