The sky was not very high up, or the gods were lower than today, so people believed if you could build a shrine sufficiently high, then the gods would come to live, and priests could entertain them with music, dancing, fine foods, flatter them with praise, and appeal to them for favors. Maybe something could be done to improve the weather, and the harvest, or maybe the city had an enemy who deserved misfortune.
King Ur-Nammu built the ziggarat of Ur for Nanna, the god of the moon. The ziggarat was named “house of the great light.” The ziggarat made Ur the abode of Nanna, the lord of wisdom, who knew all the stars foretold, and who controlled the Euphrates.
Gilgamesh ruled the city-state of Uruk. Agriculture, massive irrigation projects, domestication of animals, specialization of crafts, development of writing for accounting, law, history, and art, a full-time bureaucracy, a standing military, merchant and professional classes, and a hierarchical society with the gods at the top derived from this time and place. Anu was the one on high, the sky god, the ancestor of all other gods and earthly kings, the source of all authority. The White Temple at the top of the Anu ziggurat was the temple of Anu, visible for a great distance, a symbol of great power. In its foundation were buried bones of a leopard and a lion. Its whitewashed walls blinded everyone with its light.