As Robert de Monte says that Henry I. built many castles in England as well as in Normandy, we naturally ask what other English keeps besides Rochester may be assigned to him. It appears to the writer that Corfe and Norwich keeps may very likely be his. Both were royal castles in his time, and both were originally wooden castles on mottes.[1156] Both these castles have forebuildings, and neither of them have floors supported on vaults.[1157] Corfe has very superior masonry, of larger stones than those used in the keeps known to be Henry I.'s, but wide-jointed. At Norwich only a very small piece of the original ashlar is left. Corfe is extremely severe in all its details, but quite corresponds to work of Henry I.'s reign.[1158] Norwich has a great deal of decoration, more advanced in style than that to be seen at Falaise, but still consistent with the first half of the 12th century. Neither keep has the least sign of Transition Norman, such as we seldom fail to find in the keeps of Henry II. Moreover, neither of them figure in the _Pipe Rolls_ of Henry II., except for repairs; and as Stephen in his harassed reign can hardly have had any money for building stone keeps, we may with some confidence ascribe these two keeps to Henry I. A few words should be given to the castle of Gisors, which contains in itself an epitome of castle history. The first castle, built by William Rufus in 1096, was undoubtedly a wooden castle on a motte, with a stockaded bailey below it; certain portions of the present bailey walls rest on earthen banks, which probably belonged to the original castle, and show what a much smaller affair it was than the present one. Henry I., Robert de Monte tells us, strengthened this castle with a keep. Probably this was the shell wall which now crowns the motte; the smallness of the masonry (stones about 5 inches high, rudely dressed and coursed) and the slight projection of the buttresses (9 inches) agree with much of the work of his time. There would be a wooden tower inside.[1159] The chemise or shell wall is pierced by loopholes, a very unusual arrangement; they are round arched, and of very rude voussoirs.[1160] Inside this shell there is a decagonal tower, called the Tower of Thomas à Becket, which is almost certainly the work of Henry II.,[1161] as its name would indicate; the chapel of St Thomas is close to it. A stair turret of the 15th century has been added to this keep; its original entrance was, as usual, a door on the first floor, but a basement entrance was built afterwards, probably in the 13th century. Philip Augustus, after he had taken this castle from John, added to it one of the round keeps which had then become the fashion, and subsequent enlargements of the bailey converted it into a "concentric" castle, of which the motte now forms the centre.