Looking into the direction of its southeast corner, note the stairs to the left.
One of some pictures of what I call the south end building. On the map it's Tower M.
I do not know more about it. It has a couple of what must have been windows from the start, as well as some large holes in its walls that probably are results of neglect or attack. A staircase leads to its top. One can see there is some substructure that I did not dare enter.