Stone walls have been part of the landscape of Mação since several centuries. The technique is the same along the time, handed down from father to son.
Experience in built stone walls helps to know how to choose on time the stones that make up a sturdy wall.
The technique is simple: create an external part of the wall with big stones, filling the interior with earth and small stones, consolidating with hammer. The difficult part is creating a regular horizontal surface for each row, so that the stones of each row overlap with those under solidly.