The Bronze Tiger Bell is the eightieth treasure that can be found in Uncharted 2: Among Thieves.
The Bronze Tiger Bell is found in Chapter 22 - The Monastery. Talk about obscurely-hidden treasures; this may be one of the best-hidden ones in the game, and one of the most difficult ones to get to as well. You have to eliminate the entire threat across the nearby bridge before attempting to get this treasure, or you'll get cut to shreds. Thus, be sure all snipers and their light gun-carrying friends are all killed. Then, in the tower with the boards leading over to the bridge, work your way down to the lowest level. You'll find a bridge severed in two down here, and the gap between the two halves of the bridge seems too great for you to jump. But if you assumed that, you'd be wrong. Start running towards the severed bridge, getting a good gallop going. Jump at the last possible moment, and Drake should barely be able to grab the far side of the broken bridge. You can then scurry forward down a ladder, continuing down some stone platforms. You'll see the treasure suspended above you on your left. Shoot it down and claim your prize before continuing.