Ziggurats (“to build on a raised area”) were massive structures erected in the ancient Mesopotamian valley and western Iranian plateau, having the form of a terraced step pyramid of successively receding stories or levels. Ziggurats were built by the Sumerians, Babylonians, Elamites, Akkadians, and Assyrians, each part of a temple complex which included other buildings.
It has been suggested that the ziggurat was a symbolic representation of the primeval mound upon which the universe was thought to have been created. Built on seven levels the ziggurat represented seven heavens and planes of existence, the seven planets and the seven metals associated with them and their corresponding colors. Only priests were permitted on the ziggurat or in the rooms at its base, and it was their responsibility to care for the gods and attend to their needs. The priests were very powerful members of Sumerian society.