A little dissapointed with this one, I got seen at the end when trying to double assassinate the brute and the regular guard, but seeing as im leaving my parents place today this will be the best I can upload.
This video shows my favorite way of approaching the captain, its entrance isn't guarded very well and is hidden in the cliffs, use the pigeon coop icon to find it. If done correctly you can sneak right behind the captain. Im also really pissed off at ACB, in my latest videos I Sneak behind them for a high profile kill, but it looks so buggy it doesnt look cool at all, Ezio pretty much morphs into him. I would be better off doing a low profile kill or something.
I might make another video showing how to clear out the entire stage of guards without being seen. I really like these later borgia towers, they are more complex if you want to take out every guard. However some of the stages respawn guards so I wont be showing those.
Still, nice vid. I wouldn't have thought of sneaking behind Prospero, but you did!