Within the bible we can see cities as symbolic representations of three different ideas. These three city figures are arranged along an itinerary that corresponds substantially to the development of the whole history of salvation.
The first time there is talk of a city in the bible is when Cain is struggling with the anguish that made him restless and always fleeing from relations with others after having shed the blood of Abel (cf. Gen 4:3-12). Not even the sign of benevolence received from the Lord reassures him (cf. Gen 4:13-16). Genesis recounts subsequently: “Cain knew his wife, and she conceived and bore Enoch; and he built a city, and named it Enoch after his son, Enoch” (Gen 4:17).
The fact is that after killing Abel, Cain is no longer willing to face other fraternal relationships. In the grip of anguish and anxiety about a probable exacting of revenge and distrust of himself and his own behavior, he wants to find in his city the haven that will allow him to look out onto the horizon of the world beyond, where he can be assured of the exclusion of fraternal contact with any presence, be it already nearby or intending to approach him.