--- promoted to front page by Ian ---
The goal is to be stealthy during the Jacobo assassination. I manage to pull it off, kind of. The guards in the Antico Teatro Romano are programmed to detect you after the cutscene. They are prestaged when you start following Jacobo and are invincible to attacks at that time. By moving them out of the Antico Teatro Romano I can avoid them attacking me. However the minimap is yellow for about a second, which means I'm exposed. But since it's yellow instead of red they technically didn't see Ezio. Here's the whole setup.
By throwing a smoke bomb and grabbing with a weapon you can avoid detection. Then you can move Jacobo to the Antico Teatro Romano (I exit the city through the north entrance since the south one has a group of posted guards). In there are some prestaged guards. Jacobo is far from his waypoint and won't move. Since I'm unable to kill them I move them out of that place.
Getting Jacobo back into the city
Here's a trick I used to get him back in Tuscany. Move close to the city wall so that Jacobo's last waypoint is modeled in the game (move Jacobo out of the Antico Teatro Romano first). Notice how the nearby group of thieves suddenly disappears? Anyway continue to hug along the wall when Jacobo starts moving (one time he stopped moving after I moved away from the wall, so this is important).
Prevent other guards from going in the Antico Teatro Romano
Shortly after Jacobo exits the city through the south entrance the game autosaves. Guards appear outside the Antico Teatro Romano and will follow Jacobo inside it. To prevent this simply start the scene before he gets in there by racing ahead of him (be sure to remain within about fifty meters).
Nice one! I really enjoyed the stunt at the end.