How can you say that the Mesopotamians were great builders?

The following points illustrate that Mesopotamians were great builders:

1. Mesopotamia gave birth to the world's first cities which were largely built of sun-dried brick.
2. The Mesopotamians created the world's first columns, arches and roofed structures.
3. Simple homes were constructed from bundles of reeds tied together and inserted in the ground, while more complex homes were built of sun dried clay bricks.
4. Cities and temple complexes with their famous ziggurats were all built using oven-baked bricks of clay which were then painted.
5. Another important feature of the Mesopotamian architecture was the large gateway of a city. The most famous of these gateways is the Ishtar Gateway from Babylon.
6. The Hanging Gardens of Babylon are described as a remarkable achievement of Engineering.