Having a ziggurat signified that a Sumerian city was?

A Sumerian city was deemed as geographically large and politically important if it had a ziggurat.

Explanation:

In ancient times, the administrative buildings and the places of worship in the city determined the significance of the cities. In the Mesopotamian civilization, a special structure called ziggurat was build to serve as the heightened platform to dispense ease while talking to God. The people then believed that God lives in the skies and in order to make him listen to the prayers, it is better to go a little closer to him by climbing up to tall places.