No city wall? And the city was destroyed by the none-too-neighborly neighbors? Call 60 minutes!
My first bumping into Lagash was in the dictionary of archaeology Penguin (at least used to) publish. Gudea of Lagash is an old favorite.
https://search.brave.com/images?q=gudea%20of%20lagash
https://search.brave.com/search?q=gudea+of+lagash&source=desktop
https://search.brave.com/videos?q=gudea%20of%20lagash
As I recall Venice was also built in a marsh for defensive reasons and had no walls.
Of course when the marsh disappears, so does your defense.