By the Cracked.com method of dating, the large Romanesque cross of Sand Damiano was made about four centuries before the events of Assassin's Creed 2. It is famous for being the cross that Saint Francis of Assisi prayed to before receiving his miraculous vision to reform the Roman Catholic Church.
Also, for inadvertently featuring a giant dong on the holiest figure in the Western world.
We should clarify: Since the San Damiano cross has become a standard for religious icons, its style has been reproduced for centuries. However, it was not until a few years ago at a church in Warr Acres, Oklahoma that somebody had looked at their reproduction and had one of those "once you see it, you can't unsee it" moments when looking at Christ's abdomen.
Take that, Satanism!