The ziggurat: Invention in ancient Mesopotamia

When man gave up the nomadic life, he often made his home in the deltas of great rivers. Though this had its advantages for trading, the weak bearing capacity of the soil caused him all sorts of difficulties for his settlements. The habitations were very light, made of reeds and branches-an aquatic architecture that was, so to speak, the harvest of the soil of the delta which, in Mesopotamia, was soft alluviurn borne down towards the Persian Gulf by the two great rivers, the Tigris and the Euphrates ( Figure 6 ). These rivers carried so much silt to the almost level plain that their beds rose with the result that, at flood time, they overflowed their banks and spread the alluvium over the surrounding land.