This is a Mesopotamian arch. Click here for the link.
The arch
Another invention was the arch. Sumerian arches were inverted U- or V- shaped structures built above doorways. The Sumerians built arches by stacking bricks made of clay and straw so that they rose in steps form the walls until they met in the center. Arches added strength and beauty to Sumerian buildings. Arches became a common feature of temple entrances and upper class homes.