“One extraordinary feature of the private quintas or orchards and plantations in the vicinity of the Saladeros was the walls or hedges. These were built entirely of cows' skulls, seven, eight, or nine deep, placed evenly like stones, the horns projecting. Hundreds of thousands of skulls had been thus used, and some of the old, very long walls, crowned with green grass and with creepers and wild flowers growing from the cavities in the bones, had a strangely picturesque but somewhat uncanny appearance.”