Ac 2 v 21 - Political Suicide
0Unlocked After: Sequence 5 - Memory 1: Four to the Floor
The target is somewhere near the Church of San Lorenzo. Follow the green target on the Mini-Map to reach the area. He's easy enough to spot -- he's the guy surrounded by a boatload of guards. Activate Eagle Vision and look in the tunnel that has a red blip at either end to identify the target.
Getting at the target is easy enough. First, look for a group of Courtesans to hire. Then, lock on to one of the guards on either side of the tunnel and order the Courtesans to distract him. The guards gathered on this side of the target will move away to socialize with the Courtesans -- now's your chance! Move in there and use your Hidden Blade to assassinate the target. - https://www.supercheats.com/guides/assassins-creed-ii/