The game strategy center of Age of Empires.
Many people tend to build more wall segments then is in fact needed.
Here are some helpfull tips on what you need to do to wall up with the minimum amount of stone and fuss. Corner walls are not needed, you should build your walls in lines only, not in corners, and when connecting two lines avoid making the corner, as often your peon will get stuck at the corner and if your not watching the wall wont get built. Shallows can be walled off more easily then most realize. As in the picture below, the highlighted section of wall is the last needed to wall off that shallow. Again, units can not move diagonaly, and it would be impossible for a unit to cross those shallows.