Babylonia was an ancient state located in Mesopotamia along the Euphrates River. The city of Babylon, founded over 4,000 years ago, grew to become one of the largest cities of the ancient world under the rule of King Hammurabi in the 18th century BC. Hammurabi is best remembered for enacting one of the earliest and most complete legal codes, known as the Code of Hammurabi. Some of Babylonia's major accomplishments included developing the first positional number system, laying the foundations for Western astronomy, building massive structures, and contributing significantly to Mesopotamian art and literature.