The online Crossfire map has an excellent sniping location. The spot 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 the 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. You can then work your way up to the perfect sniping position.
On the Marine's side (top of the hill), go into the sniping building (the back building that everyone goes to). Go to the very end, climb up the ladder, and at the top, stop, turn around, and there will be two blue balconies. Sprint jump onto one. You can climb into either of them. From here you can snipe nearly all of the right-hand side.
On the OpFor/Spetznas side (bottom of the hill), reach the top of the three story building in Normal mode. You will need RPGs. Go to the second floor and climb onto the chair, then jump slightly to the left against the wall to get onto the ledge. Sprint jump onto the third floor. This is difficult to do. Stand on top of the slanted piece of roof, but in the center of it. A tiny chunk is missing. Take out an RPG and aim down into the street. At the same time while holding LB Xbox 360 , aim, jump, backwards and shoot. If done correctly, you will be on top of the three story building. Note: Helicopters can see you.
In the destroyed Bistro at the bottom of the hill, stand on the counter (ground floor). You can look out in between the wall and the roof. From here you can snipe the Marine's buildings.