King Ur-Nammu laid the ziggurat"s first brick in 2100 BCE, and construction was later completed by his son King Shulgi, by which time the city was the flourishing capital of Mesopotamia. But by the 6th Century BCE, the ziggurat was in ruins thanks to the desert"s extreme heat and harsh sand. King Nabonidus of Babylonia set to work restoring it around 550 BCE, but instead of re-creating the original three tiers, he built seven, aligning with other grandiose Babylonian structures of the time, such as the Etemenanki ziggurat, which some believe was the famed tower of Babel.