There is to be remarked in this keep, the absence of a cross wall, the basement filled up with earth, the unusual projection of the four turrets, the probably distinct entrances from the forebuilding to the ground and first floor, and the well-stair, nearly as large as that of the Tower of London. Also, there is no portcullis, and there are but few mural chambers or galleries. This is the more remarkable as the walls are unusually thick and the material excellent. Further, there are no fireplaces in the three remaining walls, and there is no ornamentation of any kind, inside or outside. The keep is the only distinctly Norman building remaining in the inner ward, although much of the curtain is Norman, and more rests upon the Norman lines. It has been stated that the keep forms the north-eastern angle of the inner ward. The curtain abutting upon it on either face is of its own date. At the north-west corner the curtain forms the north wall of the forebuilding, and for some yards is original. At the south-east corner of the keep are the remains of the entrance into the inner ward. This, as at Bridgenorth, was a doorway in the east curtain, close to the keep, and, as at Bridgenorth, although the curtain has been removed, a part of the doorway remains. The curtain was here 11 feet thick and 21 feet high to the rampart wall, above which were a parapet and rear wall of about 5 feet more. One whole jamb and the springing-stones of the portal remain. There was no gatehouse, only an opening in the wall, as at Ogmore, and probably at Ludlow. The defences were:—First, a portal 3 feet deep, and in it a square portcullis groove; then a rebate for a door opening inwards; and, finally, an arched passage 3 feet higher than the portal and 6 feet deep. The entrance appears to have been a foot-gate only, so that carriages could not enter the inner ward.