Of the central tower, the south-east pier has been rebuilt; the north-east and south-west piers have been cased. The north and west arches of the tower survive; the south and east arches have been rebuilt. The nave was considerably wider than the central aisle of the choir; the tower was therefore not built square; the northern arch being set obliquely, and not parallel to the southern one. Outside, however, the north side of the tower is corbelled out till the tower becomes square. [Illustration: NORTH TRANSEPT.] The design of the choir is best seen in the east side of the north transept, which retains the original round-headed windows. In the choir the western windows of the north aisle were converted into lancets in the thirteenth century. The design of transept and choir is almost Greek in its severity. Very effective is the contrast of broad wall-surface and plain splayed window with the light and slender shafted arcades of triforium and clerestory. In proportions, too, it is superior to nearly all later designs. The pier-arches are tall and narrow, and the triforium thoroughly subordinated to the tall clerestory; the proportions approximate closely to those of Westminster Abbey and Beverley Minster. It is remarkable, too, for the studied absence of foliated ornament. Not that the builders could not design a foliated capital; they have left one or two, in unnoticed corners of the north transept, to show their powers. All the capitals of the choir are moulded capitals, as at Roche Abbey—perhaps occurring here for the first time. Being a first attempt, they can hardly be considered a success; they were soon to be improved upon in the French crypt of Canterbury. The designer relied on architectural effects pure and simple, and was followed in his ascetic self-restraint sixty years later in the eastern transept of Fountains and at Salisbury. Even more remarkable is the complete abolition of Norman ornament. The billet, the zigzag, the whole barbaric congeries of Norman ornament is contemptuously cast aside. In this respect, indeed, Ripon is much more advanced than Canterbury choir, which was not commenced till 1174. The clerestory, however, is of a familiar Norman type, being an adaptation of that of Romsey and Waltham Abbey, and Peterborough and Oxford cathedrals; it was reproduced a little later in Hexham choir. The vaulting-shafts rest on the abaci, French fashion. In the choir there are five vaulting-shafts, which in the clerestory diminish to one. The effect is not satisfactory, and a different treatment is adopted in the transept. It is noteworthy that the vaulting of the north transept aisle contains an exceptionally early example of ridge-ribs, both longitudinal and transverse.