Call of Duty 4

On Top Of Buildings in Ambush

When you spawn out go to the tank on the side with out the Hummers, the second before the last.
Find the teddy bar and then jump on the left corner of the sewer hole and go straight for the wall, your character should climb the wall.
Once up go to the far right of the top section of the code and then there will be a sandbagged window.
Then sprint and jump out toward the next broken in building, and there's a good spot for almost any game type.