The first cities

Cities have existed since the beginning of recorded human history. This was cultural and technological change.
The first villages came with the beginning of agriculture in the Middle East about 10.000 years ago. Trade was an important thing for a larger towns and cities.
In cities like Mesopotamia (Tigris and Euphrates) or Egypt (Nile) when there is a big river near a city, people started to build dams to protect them from a floods. They were digging a big rows where water could drain to other places. With this technology, farmers could move to other areas. People did a special calendar and they know when the floods would come to reap most of benefit.

First cities were more than composed of workshops. They had a lot of monumental structures. The great planned cities of the Indus valley build around 2600BC had a water-saving system.
All different classes lived in other parts of the city.