Which was the first city of Mesopotamia and who was its ruler?

Eridu, Uruk, Kish and Nippur were among the earliest cities of Mesopotamia. These cities had their own Government and rulers. The word "Lugal", which means "the big man" was used for the ruler of Kish. In around 2700 B.C., Uruk was the first city protected with a wall and had a ruler titled as "En".