Go to the building where you have to go up a ladder.

Go left and you see a hole overlooking the courtyard.

Go towards it and jump.

Then, slightly move left and you will land on a ledge.

Go forward a bit and you will see part of the ledge slanting diagonally.

Go towards it and line up and stand on it.

Then you will see a white archway with a red bit. Jump and try to land on it.

Then turn left and go forward and follow it until you reach a building.

You can now go round it and survey the area.

Beware: you can be sniped!