The keep is cylindrical within, and has a basement and three upper floors. All its original openings seem to have been either flat or round-headed. There is no original pointed arch; that over the main door is clearly an insertion. The basement is on the ground level, about 20 feet diameter, and the walls about 10 feet thick, and it is covered in with a flattish dome of inferior rubble, but probably original. On the south side are traces of a fireplace, of which the vertical tunnel remains in the wall. The entrance-door is on the west side, and so also is the main door. It is much broken, and has at present a late flat-pointed arch, but it seems to have been round-headed. It opened not, as now, from the court, but from the passage-room leading to the postern. In the outer wall, a couple of yards to the right of the door, is a recess like a sepulchre in the keep wall, and in it is laid a stone coffin, probably found in the outer ward. The recess may have been a seat; it can scarcely have been a tomb. The entrance-door has no portcullis. In its left jamb a flat-topped mural passage, 3 feet wide, leads into a garderobe which projects outwards between the keep and the curtain, and has a short exterior loop. The shaft of a garderobe in the floor above so drops that it is evident that here, as at Corfe, there was a wooden partition within it. Entering the keep, on the right a door leads up half a dozen steps into the north side of what is called the guard-chamber, a barrel-vaulted room, 14 feet east and west, by 7 feet, with a loop to the south. This looks very much like an oratory, though it is a passage-room. It is contained partly within the spur buttress, and is evidently the cause of that appendage. From near the west end of the chamber, a second door leads by a mural stair, 3 feet broad, to the first floor, a circular chamber, 21 feet diameter, with walls about 8 feet 6 inches thick. This stair opens by a narrow, round-headed door in the jamb of a doorway, also round-headed, which seems to have led from this floor into the “great chamber,” the withdrawing-room of the hall. In the opposite door jamb, a similar door leads by a mural passage to a garderobe above that already mentioned. The first floor was evidently the state-room. It has traces of a fireplace to the south side, but the hood is gone, and opposite to it is a round-headed window of 4 feet opening, looking up the Tees. Another window, probably of the same pattern, looked towards the tower ward. This has been altered to suit a Tudor five-light flat-topped window. This seems to have been called “My Lady’s Chamber.”