A Viewpoint provides a great view of Pharos Garrison, which is situated at the end of an island, north of Alexandria. You must sneak through the base to reach the high vantage point (once synchronized, you can Fast Travel here).
One treasure is located on the tower’s eighth floor, just inside the southern, barred window. Climb up the tower’s south side to the platform with the white canopy. Enter the opening. Follow the spiral walkway up a floor to find the treasure. The second treasure is in the tower’s top room, just below the fire. Mark the captain and commander early and keep tabs on them. They move all around the area—on the outer wall and below.