What role did religious structures, such as temples and ziggurats, play in a Mesopotamian city?

Ziggurats were built for local religions, and were raised platforms in temple complexes that had many rooms and chambers for temple priests to take care of the God and Goddess. They were built with a thought that the temples will be closer to heaven and also Gods.

Explanation:

this forms a narrow, steep sided inlet (sometimes deeper than 1300 metres) connected to the sea. the terminal moraine pushed down the valley by the glacier is left underwater at the fjord’s entrance, causing the water at the neck of the fjord to be shallower than the main body of the fjord behind it.