Celestia is a mysterious location that very few people understand. It is the floating island that can be seen in the sky above Teyvat, and the residence of the gods.
It is said that only mortals who perform great, heroic feats can ascend to Celestia and achieve godhood, where they will watch over their people from above. A human with a Vision is an allogene — one with the potential to reach godhood. However, Celestia is much more than that - a symbol of divine oppression.