The door of the ground floor, apparently 4 feet wide, and with very late dressings, is at present in the west wall, here 9 feet thick, and may possibly have been always there, although certainly not in its present form. It was covered by the exterior stair. It is placed nearest to the south end, between the second and third pilasters.
The stair, 9 feet broad, is built against the west face of the keep, without bond, and perhaps a later addition. Beneath it is a large open arch, round-headed, springing from flat pilaster jambs, which, continued above the string or cap, panel the soffit of the vault. This arch serves as a porch to the door of the basement of the keep.
The stair terminates in the staircase tower, a rectangular lean-to, or fore-building appended to the keep, forming a vestibule to the main entrance, and said to have carried the stairs leading to the upper floor. It is about 19 feet by 16 feet within, and has a stone bench against its north wall. The door from the exterior stair in the north wall is round-headed, 6 feet 6 inches wide, opening in a wall 6 feet thick, the other two walls being 4 feet. The keep door, between the first and second pilasters, and therefore near the angle of the keep, has been 6 feet broad, now enlarged to 9 feet. It has a flat top, with a semicircular arch of relief in the wall above, not intended to be seen. There was probably a door in the south wall of the vestibule opening upon the great bastion, and there are traces of a covered passage from it into the garderobe tower. This vestibule seems certainly to be of the age of the keep, and to have been occupied by a staircase to the principal floor.
The keep was divided into two great chambers by a wall 6 feet thick. The basement was covered, and the first story floored by ten large whole-timber joists, the cavities for which remain in the south wall. The first floor probably contained a chamber, 42 feet long by 28 feet broad, and 24 feet high, which, however, must have been very dark, since the north wall was interior, and the south without windows. Two small doors, probably of rather later construction, open through the south wall into the exterior gallery.
Above this room, forming the third story, was another, apparently of the same size and much more cheerful, and which may have been the hall. A well-stair led from this upwards, in the east wall, near its south end. The water-tables within show a ridge and valley roof, as at Porchester, and probably there was originally nothing above this floor.
The battlements, with a slight exception, are gone, but in the east and west wall, just below the battlement line, are coupled Norman windows, of about 3 feet opening, a pair between each pair of pilasters, thus forming a sort of arcade, not unlike the far later ones at Swansea and Llanphey, but much of which seems always to have been closed. It is remarkable that a building so massive, and the walls of which are so thick, should have been without the usual galleries and mural chambers found in Norman keeps.
Mr. Bond, who is intimately acquainted with this castle, and has brought much critical knowledge to bear upon its details, is of opinion that the upper part of the wall of the keep shows evidence of having been an addition to the original structure, though at no very long interval of time.
Built against the exterior of the keep, on the south side, and projecting into the outer ward, is another lean-to, or appended tower, of about 30 feet in breadth and 20 feet projection. Outside it has three pilaster strips and one on each flank, rising from a common base. At present it reaches only to the floor of the second story of the keep, but it seems to have been higher, and is said to have been lowered by Sir C. Hatton. It is a garderobe tower, and contains on each of its two floors two chambers of about 7 feet by 9 feet. The upper are not accessible; but it is clear that a portion of the eastern lower chambers was bratticed off, to carry the refuse from the upper. In the western chamber is a stone arch, which may be taken to indicate the place of this brattice. The eastern is open on one side, and was evidently closed by a timber partition. These chambers terminate below in two square openings, on the face of the tower, and this supports the notion that the western as well as the eastern chamber was intended for a garderobe.
Between these chambers and the keep wall runs a vaulted gallery, into which they open, and from which two small doors, already mentioned, enter the first floor of the keep. Although the garderobe tower covers only half the face of the keep, this gallery is prolonged over the whole, being protected by a wall, looped. A door at its lower or east end led towards the kitchen, and one at the upper end opened on the great bastion, with access on the right to the vestibule, and on the left to the curtain leading from the keep to the middle gatehouse. Two water-drains from the keep cross the gallery and discharge into the garderobes.
This tower, being built against and not bonded into the keep, is evidently later, but resembles it in general style, and must have been added within a very few years. The explosion which shattered the keep has made evident the complete want of bond between the two buildings.