I recently played a game in which, although I conquered every civilization, I kept the Barbarican-captured city of Madrid intact. My civilization score seemed to be a lot higher than it should have been when based upon my population, wonders of the world, etc. Perhaps there is some correlation between completing the game alongside of a Barbarian city and this high score. I will expedite the testing of this theory tomorrow by using the cheat menu. Has anyone ever encountered a similar experience?