Templar (one of the strongest and most wealthy Crusader forces) sweet-talked their way into some swanky headquarters on the Temple Mount, one of the most important religious sites in Christianity, Judaism, and Islam. Kind of a big deal. What made it an even bigger deal was that the Temple Mount was supposedly the location of the fabled Solomon's Temple, and conspiracy theories abound that the Templars found something incredibly important there. By which I mean proof that Jesus survived the crucifixion and married Mary Magdalene. Basically the oldest celebrity gossip in existence.
Assassin's Creed says not only is Solomon's Temple real, but what it contained is way crazier than some dusty old scrolls. Inside the Templars found a Piece of Eden, a tool that ancient beings used to control human minds. (In a very lovely gold chest, too. You'd think someone would have noticed that sooner.) Finding was all the Templars did with it though, since your first act in Assassin's Creed I is to nab the thing and head for the hills. SUCKEEEEEERS.
