Assassin's Creed 2 Walkthrough

With the enemies dead, climb the tower ahead and take out the two guards at the top. From the top of the tower, you can make a leap of faith into a hay stack below.

There are more enemies on the next stretch of parapet, so expect a fight before you can climb up the next tower. And again, at the top of the second tower are more enemies to kill, and another leap of faith to make into a pile of hay at the bottom. When you land in the hay here, however, don't get out. There's a series of guards patrolling the parapet walk and you can take 'em all out with stealth if you're careful. Wait in the first pile of hay as one guard patrols by and assassinate him silently. Then, when the coast is clear, move out to the second pile of hay for another assassination.

Climb to the next tower and hang on the ledge, waiting for a patrolling guard to come near so you can pull him over the edge. Two other guards are facing the opposite direction and you can double assassinate the pair by running up behind them. Jump off the other end of the tower and you can get the jump on another guard that's standing by his lonesome.

There's one more massive batch of guards to fight off in the next area. Be prepared for a grueling melee and use all of your skills to fight off the attackers. When you've cleared the yard, climb a nearby scaffolding to a level up above where you'll find a switch that opens a gate into the Vatican.

From this point on, you can't be spotted or it'll be an automatic game over for you. Fortunately, the only folks around that know you're not supposed to be there are the guards. The priests, dressed in their dark robes, have no problem with you walking in the middle of their circles to hide. In the first hall, skip between circles of priests to get down the hall. There's one group of priests that patrols around the hall. Jump in their group and tag along to reach the far end of the hall.