Final answer:
The ancient structure associated with the Ishtar Gate is the Ziggurat of Ur. It served as a shrine to the moon god Nanna and was used for administrative purposes.
Step-by-step explanation:
The ancient structure associated with the Ishtar Gate in Babylon, Iraq is the Ziggurat of Ur. Ziggurats were massive step-shaped pyramids with a shrine or temple at the summit. They were built in Mesopotamia and were used for religious purposes by priests. The Ziggurat of Ur, built by King Ur-Nammu, served as a shrine to the moon god, Nanna, and was also used for administrative purposes.