The online Crossfire map has a very good sniping location. The location can only be reached when you are playing the old school free 4 all section. Notice the building at the very end of the map on the opposite side of the bus. You can get to the very top of the building that is around the corner. First, get to the second story where the chair is found. Get on the top of the chair facing the wall and jump. You may have to run and jump, but eventually you will catch an edge. Then, turn to your right and move your way up the ledge. When you hit the wall, stop, take two steps back, and turn to the ledge on the same level with you northeast. Pick out the spot with no rubble on it. You must run and jump to reach the ledge. If you fail, try again. When you get up there, turn left and note the slanted giant piece of rubble. Run up it, turn right, then jump and catch the ledge then jump again to get up. Turn right and move to the wall of the building. Touch the wall, then turn left and move along extremely close to the wall. Do not go straight as you need to get around the corner and continue until you reach the next corner. Turn right and go straight until you get stuck on the window. Move slightly to the right until you can move forward. As soon as you are past this window sill, go back close to the wall and turn left. Look down at the barbed wire fence. While against the wall, run past this fence. You should drop out of the map but still be able to play. Do not enter the white parts of this area or you will die. Only go out of it if you want to return to the normal map. This area is a good place to snipe players without them knowing you are there. You are not invincible; other players can still shoot you.