Another variety of the Cylindrical Keep was that at Orford, in Suffolk, which possessed a cylindrical shaft similar to that at Conisborough, and was supported by three minor towers symmetrically arranged and carried above the battlements. This Keep was protected at the base by a massive wall with a ditch between the wall and the Castle base, and probably suggested the Conisborough Keep and also that at Warkworth, while those at Wallingford, York and Pontefract approximated to the same ideal. CHAPTER VIII THE CONCENTRIC CASTLE, _c._ 1250, TO THE CASTELLATED MANSION PERIOD The inception of the concentric idea in castellation must not be ascribed to the English builders of the second half of the thirteenth century, inasmuch as the plan is essentially oriental and appeared in the Levant before 1200. Thus Château Gaillard, built by Richard I. in 1196 upon the banks of the Seine near Les Andelys, is based essentially upon the concentric type, though it does not absolutely conform to that ideal owing to the configuration of the ground. That crusading monarch was among the first to recognise the possibilities of the Saracenic form and based this castle upon it. Upon the only side where it could be attacked it offered first an outer triangular-shaped ward, with an encircling wall, having five towers upon its enceinte. Between this and the second ward was a formidable ditch, 30 feet in depth, the wall standing upon the brink of the scarp; this second ward was of large dimensions with five towers upon its walls, which were practically built upon the edge of precipices. It was roughly hexagonal in shape and contained the inner ward, partially circular in outline and surrounded by a ditch. The walls of this ward were lofty and faced with bastions segmental in plan, thus embodying the prevailing belief that angles and corners were more vulnerable than curved surfaces. Inside this ward stood the Keep, forming the fourth successive line of defence to be overcome. The Keep or Donjon is splayed outwards at the base, a device often adopted for projecting missiles among the assailants when dropped from above, and also for greater strength. Probably the earliest examples of machicoulis are found upon this Keep. This formidable fortress fell by a combination of mining, filling up of the great ditch, battering the Keep, and escalading the inner ward, after pounding the curtain walls with perriers. The thousands of warriors returning from the many crusades were well acquainted with the Concentric Castle, having in many cases been detained before the walls of an eastern city built upon a similar design. The difficulty and danger in attacking such a place were well known to them, and we can only ascribe the question of cost as the chief reason for the non-adoption of the idea at an earlier period.