Trayastrimsa, Tavatimsa in Pali, is named for its government: thirty-three gods share its rule, Sakka presiding over thirty-two co-regents. The number is older than Buddhism, inherited from the Vedic convention of thirty-three gods, and the Buddhist texts supply a characteristic origin story: Magha, a virtuous man of Macala village, and his thirty-two companions spent their lives in public works, building roads and rest houses, and were reborn together atop Mount Meru as the heaven's founding administration, Magha becoming Sakka.
The location is the old cosmic mountain's summit, which makes Trayastrimsa the highest heaven still touching the world's central axis; above it the heavens float free. Its geography is lovingly detailed: the city of Sudassana, the Vejayanta palace, the parijata tree whose blossoming marks the celestial seasons, the stone throne of Sakka that warms when a virtuous being below needs help. It functions in the canon as the default paradise of merit, the heaven ordinary generosity aims at, and simultaneously as a battlefield: the asuras, expelled from it in the founding coup, assault it perennially from the mountain's base, and the war of gods and titans that other mythologies place at the beginning of things is here a running municipal problem. Its days last a hundred human years, its residents live a thousand such days, and, as everywhere in Buddhist cosmology, the lease expires.