Once you find your assassins' hideout, a castle owned by some guy named Ramirez, you're tasked with phase 2 of the mission: robbing him of everything he owns.
It's unexpected. You feel like the mission should be over now, but instead it feels like two missions-in-one. (But what did you expect? How else could this have ended?)
The Ramirez mansion is much easier to solve than the streets. There are only a handful of guards patrolling the top floor, which means you can control the entire area very quickly. In contrast to the really thoughtful city street design I analyzed earlier, this interior floorplan is simple and comprehensible, the main corridors are narrow and arranged somewhat symmetrically, and many of the floors are made of relatively muted stone.