Mumbo's Mountain, probably one of the single most iconic tutorial levels in gaming history. Grant Kirkhope's amazing music skills also really compliment this level, as it kind of becomes a slog to play through once you get a good handle on how Banjo-Kazooie plays. Don't get me wrong, it's not a bad level, but it can get boring quickly.
All objects in the image, and the characters were created by Rare, and belong to Microsoft. The song used is Mumbo's Mountain, from Banjo-Kazooie, although the cover from Banjo-Kazooie: Nuts & Bolts is used, both composed by Grant Kirkhope.