WOw, so culture penalty isn't related to the population, but more the culture of the buildings present?? I might consider knocking down a few more of these foreign buildings then!! Previously, I've just been using the other culture's buildings and bonuses to train and retrain my troops. No wonder I've been having some issues with public order...

Exterminating might not be such a good idea then, if you want to replace another culture's advanced buildings. One you knock them down to improve the culture penalty, the population won't be high enough to re-build your own...

Thanks for the information Jerome.