The donjon and the towers of the enceinte were also bratticed at the rampart-level.97 Indications of this practice are common in military architecture abroad. The cylindrical donjon of Laval (80), a work of the twelfth century, is covered with hoarding which is supposed to be contemporary with the tower. The stone corbels which carried the hoarding of the great thirteenth-century tower of Coucy remain; and a row of plain arches pierced in the tall parapet show how the gallery was entered from the roof (81). The somewhat earlier round tower at Rouen was restored by Viollet-le-Duc on the lines of Coucy, with a conical roof and hoarding. The inner wall at Carcassonne and the curtain of Loches, among other examples, keep the holes in which the joists of the hoarding were fixed; and the walls of Nuremberg are still covered with inner galleries or coursières. The practice of supplementing stone walls with timber defences lasted till a late period; but, even before the end of the twelfth century, corbelled-out parapets with machicolations appeared in isolated instances. In subsequent chapters we shall see how military masons and engineers applied their architectural skill to meet the problems which siege-engines of greater strength and tactics more finished than those of the past forced upon them. We have now to deal with earlier efforts, which we have to some degree anticipated.