Tavattimsa is on top of Mount Meru. It is the second of 6 Deva worlds and level 6 of 31 Planes of Existence.
7)The Thirty-three Gods (tavatimsa deva) Sakka, a devotee of the Buddha, presides over this realm. Many devas dwelling here live in mansions in the air. The second of the six deva-worlds, the first being the Cātummahārājika world. Tāvatimsa stands at the top of Mount Sineru (or Sudassana). Sakka is king of both worlds, but lives in Tāvatimsa. Originally it was the abode of the Asuras; but when Māgha was born as Sakka and dwelt with his companions in Tāvatimsa he disliked the idea of sharing his realm with the Asuras, and, having made them intoxicated, he hurled them down to the foot of Sineru, where the Asurabhavana was later established. The chief difference between these two worlds seems to have been that the Pāricchattaka tree grew in Tāvatimsa, and the Cittapātali tree in Asurabhavana The chief features of Tāvatimsa were its parks - the Phārusaka, Cittalatā, Missaka and Nandana - the Vejayantapāsāda, the Pāricchatta tree, the elephant-king Erāvana and the Assembly-hall Sudhammā (J.vi.278; MA.i.183; cp. Mtu.i.32). Cited from Website: Tavatimsa