Yes, I know what you're thinking. A project on a video game? Well the wishful thinking has become a reality for me! I am doing my history project on the historical accuracy of Assassin's Creed II and I thought to myself "If this is a video game, and I am apart of a video game website, why not ask the folks of Giantbomb if they have any suggestions?" And that is what I do now. So if you happen to know any sort of detail concerning this game that would perhaps be good in an essay under the subject  "How historically accurate is Assassin's Creed II?" The help would be appreciated! 
Thanks!

Well the pope you beat up was in fact the pope.

I understand that the cities in AC2 are accurate to how the cities were back during the renisance, and in fact are still pretty close to the way they are today.
 
Many if not most of the characters in that game are in fact real people.
 
I also found this website using a fast Google search that you probably did yourself. Hope it helps:  
 http://blogs.ign.com/UbiAssassinsCreed/2009/11/13/132309/  (Copy into address bar to find it...just don't Plagiarize)

Also as I understand it the DLC called Bonfire of the Vanities is based on a real event. You might want to do a bit on that. :)