The plan of the castle, as it exists at the present time, is shown in our engraving; and it will be seen that five distinct periods in the architectural history are indicated by varieties of shading introduced into the outlines. The extreme extent of the walls from east to west slightly exceeds 1,000 feet; while that from north to south is somewhat less than 600 feet. The varied outline of the space enclosed within the walls, which in a great measure has been determined by the nature of the ground, in an infinite degree enhances the equally noble and picturesque aspect of the edifice. The figures in the plan refer to the various parts of the castle in the manner following:—1, is the Barbican; 2, the Gateway to the second Baly; 3, the Octagonal Towers; 4, the Norman Gateway; 5, the Grand Staircase; 6, the Guard Chamber; 7, the Principal Ante-Room; 8, the Library; 9, the Saloon; 10, the Drawing-Room; 11, the Dining Hall; 12, the Chapel; 13 and 14, State Bed-Rooms, 15, Boudoir of the Duchess; 16, Kitchen; 17, Estate Offices; 18, Laundry; 19, Guest-Hall; 20, Stables; 21, Riding-School; 22, West Garret; 23, Abbot’s Tower; 24, Falconer’s Tower; 25, Postern Tower; 26, Constable’s Tower; 27, Ravine Tower; 28, East Garret; 29, Warder’s Tower; 30, Auditor’s Tower; 31, Clock Tower; and 32, the Avener’s Tower. Thus, the open ground within the circumvallation, as will be seen by the plan, is divided into two irregular spaces, the outer and the inner Baly, the outer being toward the west. Occupying a central position is the Keep, a grand cluster of towers and curtain-walls, enclosing an open court-yard: of these towers, the new Prudhoe Tower, within which is the Library (No. 8), with its lofty banner-turret, is the most conspicuous. Running south, commencing with No. 13 and extending to No. 2, a new range of buildings connects the Keep with the early Percy gateway between the balies, and with the main southern curtain. In this direction, all the buildings, from No. 29 to No. 17, and from thence (with the exception of No. 31, which is one of the flanking towers of the main curtain) to No. 19 southward, and to No. 21 westward, are new, and they have been erected beyond and without the limits of the proper fortification. In like manner, the whole line of curtain-wall, from No. 24 to No. 25, is new. To the north of the Keep the ground falls somewhat rapidly in the direction of the river; from the bridge which here crosses the Aln, the view of THE CASTLE, as its groups of towers and its far-extending walls rise proudly above the encircling woods, is particularly fine and impressive.