Sumerian cities came under the control of Ur-Nammu, ruler of Ur, towards the end of the third millennium B.C.
To show his power, Ur-Nammu built lots of monuments for the gods, including quite a new type of building called a ziggurat.
A reconstruction of the ziggurat at Ur.
The ziggurat was a huge platform with a series of smaller platforms on top. It looked like a stepped pyramid with stairs leading to the summit where there was a small temple.
It was a mud-brick mountain where the god could live!