There are several good sniping positions on this map. The first is a small room overlooking the garden and the front staircase. To get to this room, either climb the ladder or go up the stairs. The second location is a tiny room that has a clear line of sight into the room mentioned above. To get to this room, go to the bottom of the map and climb up the staircase. You should be on a wooden porch that connects to the gardens. Turn left and you will be in the room.
Enter the small room at the bottom of the map (the one that does not have a ladder leading towards it) and find the piled-up boxes. Climb onto the smallest box, then hop up to the top. From here you can snipe opponents without anyone actually spotting you. Also if you face the doorway, you can shoot people who try to get to you.