WORLD CIVILIZATION

Detailed explanation-1: -› Another technological advance was the arch. Sumerian arches were inverted (upside down) U-or V-shaped structures built above doorways. To build arches, the Sumerians stacked bricks made of clay and straw so that they rose in steps from the walls until they met in the center.

Detailed explanation-2: -The materials used to build a Mesopotamian house were similar but not exact as those used today: reeds, stone, wood, ashlar, mud brick, mud plaster and wooden doors, which were all naturally available around the city, although wood was not common in some cities of Sumer.

Detailed explanation-3: -So, Sumerians began to build strong walls around their cities. The walls were made of mud bricks that were baked in the sun until they were hard. The Sumerians also dug moats outside the city walls to prevent enemies from entering the city.