why are battanian cities so damaged?

Battanian cities are perhaps the most "grimy" or overgrown settlements, which I find appealing as a style. I've also noticed that they often feature broken towers and crumbling walls. Why is that, exactly? Historically, Battania and its cultures once ruled much of Calradia. However, the Empire later conquered their lands and fortified the cities further.

We know that after the events of Bannerlord, Battania was overtaken by its neighbors. Still, I don’t think they would have simply let their fortifications "rot" away, as they didn’t really experience a downfall like the Empire, where they were once great but then couldn’t uphold their infrastructure anymore. So, why exactly is this the case?