Pyramidal, stepped temple tower characteristic of the major cities of Mesopotamia between 2200 and 500 BC. It was built with a core of mud brick and an exterior covered with baked brick. It had no internal chambers and was usually square or rectangular. Some 25 ziggurats are known, located in Sumer, Babylonia, and Assyria. The best-preserved ziggurat is at Ur, and the largest is at Elam. The legendary Tower of Babel has been associated with the ziggurat of the great temple of Marduk in Babylon.