The ancient structure thought to be built by the Sumerians as a ziggurat is the Ziggurat of Ur. Located in modern-day Iraq, this massive step pyramid was dedicated to the moon god Nanna and served as a temple complex. The ziggurat exemplifies Sumerian architecture with its tiered structure and was part of a larger urban religious complex. Built during the early dynastic period, it served not only as a place of worship but also as a symbol of political and social organization. The Ziggurat of Ur remains a key archaeological site that provides insight into the religious and cultural practices of the Sumerians.