But of all the architectural improvements effected by Roger Montgomery in the wide area beneath the Keep, the most conspicuous in the present day is the great Gateway. It consists of a square tower standing over an arched way, which forms the entrance to the court, and communicates with the Keep by a raised passage carried across the moat, and terminated by a flight of steps. The upper part of this tower is supposed to be the work of the thirteenth century; but the lower portion, comprising the whole of the covered-way, retains its original stamp, and presents a striking specimen of Norman taste. The arch is circular, without a keystone, and quite destitute of ornament. The arch, as well as all that remains of the ancient front of the tower, is composed of square blocks of Pulborough stone, the angles of which still preserve their original sharpness. A portcullis was formerly placed at the outer extremity of the passage, which was probably still further strengthened by a drawbridge over the fosse immediately beneath it.[24]--See the engravings. The Barbican, or <g>Bebis’ Tower</g>, as it is generally called, is another of those warlike adjuncts by which the Norman baron strengthened and improved his new residence. It occupies the north-west side of the ditch by which the Keep is surrounded, and, notwithstanding the ravages of siege and storm, presents many of the characteristic features of Norman architecture. It is an oblong tower, supported by a huge buttress at each of its angles, and originally was of considerable elevation; but during the Parliamentary siege, about to be noticed, the upper part was destroyed, and the temporary roof which now covers it was supplied at a later period. The whole is now invested with a luxuriant mantle of ivy, and presents, like the adjoining Keep, a green pyramidal mass of foliage, through which at intervals the grey stone and white mortar are discernible. It is haunted ground-- For there, ’tis said, ’mid scenes forlorn, When midnight spreads her dreary pall, The blast of Bebis’ bugle-horn Rings loudly from its ramparts tall. While, starting to the unearthly sound, Warrior spectres gather round; And dismal through the dusky air, Banners gleam and torches glare-- Till all, at cock-crow, to their shrouds Shrink away like fleeting clouds.