Mesopotamia was an early civilization located between the Tigris and Euphrates Rivers in modern-day Iraq. Writing developed around 3500 BC with cuneiform script recorded on clay tablets. Temples called ziggurats were built as multi-layered towers for gods and administrative offices. One of the earliest works of literature is the Epic of Gilgamesh, which tells of the king of Uruk and the great flood. The Code of Hammurabi established the first codified set of laws around 282 BC with principles of retaliation and presumption of innocence. Later Assyrian and Babylonian empires constructed grand palaces and gates such as the Ishtar Gate decorated with images of dragons