Mesopotamian, and later Greek and Roman cities, were characterized by their walls and this held true of other civilizations as well.The walls of the city known as the Great Zimbabwe (in modern-day Zimbabwe) defined it and those of the city of Benin (in modern-day Nigeria) were equally considered a hallmark of that site.
Their age and continuity of habitation has been gauged based upon the foundations of buildings unearthed in archaeological excavations rather than primary documents found on site.
The population of ancient cities, depending upon which definition of `city’ one uses, differed sharply from what one might consider proper for a city in the modern day.
Professor Smith claims, “Many ancient cities had only modest populations, often under 5,000 persons” (26) while other scholars, such as Modelski, cite higher population possibilities in the range of 10,000 to 80,000 depending upon the period under consideration.
Modelski, for example, cites the population of Uruk at 14,000 in the year 3700 BCE but 80,000 by the year 2800 BCE (12).
The city of Eridu, close to Uruk, was considered the first city in the world by the Sumerians while other cities which lay claim to the title of `first city' are Byblos, Jericho, Damascus, Aleppo, Jerusalem, Sidon, Luoyang, Athens, Argos, and Varasani.