After the cut scene in 2 – Infiltrate in Uncharted: The Lost Legacy help your partner up the stairs and climb up after her.
Slide down the roof and climb to the left until you can climb up to the roof. Go forward to the ledge and jump to the wall to the right and climb over the signs to the next roof.
Jump down to the lower roof. Shimmy along the wall until you can climb to the higher roof. Jump across to the lower roof. Go through the grass and slide along the power line to the next roof and take out the guard. Pull the box out of the hut and use it to climb on top of the hut and jump to the next roof. Shimmy along the wall near the signs and use the signs to get to the next building.
Climb along it to the roof. Push the box off the roof. Jump to the next building and go around the floor until you can jump onto a beam. Climb up to the guard. Go through the building out the other side and climb up to the next level.