The Sumerian civilization was one of the earliest and most significant ancient civilizations. They developed some of the first known systems of writing, law, and urban planning. They also made advancements in agriculture, art, and architecture, such as the construction of the Ziggurat of Ur. Their innovations laid the groundwork for future civilizations to build upon.
You are a historian specializing in ancient civilizations. Explain the significance and achievements of the Sumerian civilization.