The first parts of the cathedral built (shown by black tint on Plan) were the three westmost or Norman bays of the choir, with their aisles, both the transepts, the crossing (afterwards altered), intended to receive a tower over it, and two bays of the nave, which served to form an abutment for the crossing. These portions are all (where unaltered) in the earliest style of Norman work in the edifice. The round piers and responds of the choir, the two south piers and one north pier of the nave (with their cushion caps) (Fig. 233), the main arches (with their label mouldings in the choir and transept) (see Figs. 227 and 234), the round arched and labelled windows in choir, transept, and nave (see Fig. 228), and the interlaced arcades in the latter (Fig. 235), all point to a somewhat advanced period of Norman work. The choir originally terminated with a central apse beyond the third pier (as shown by dotted line), but it is impossible to say whether the side aisles also had apses, or whether the aisle was continued round the apse. The Norman windows of the choir aisle have three external orders, with a label ornament in the outer order. The single shafts have cushion caps, and the windows are largely splayed internally. An interlacing arcade of round arches, with single shafts and cushion caps (some with volutes), runs round the north, south, and west sides of [Illustration: FIG. 235.--Kirkwall Cathedral. The Crossing and South Transept.] the transept. (See Fig. 235). The large arches leading into the east chapels were formed originally, but the chapels were built later. The lower string course of the transept is enriched with a four-leaved flower. (See Fig. 232.) [Illustration: FIG. 236.--Kirkwall Cathedral. Doorway in the North Aisle of Nave, &c.] It seems likely that soon after the completion of the above portions attention was given to the continuation of the nave westwards for several bays. The piers have the same round form as the original ones, but the caps are no longer octagonal, but round (see Figs. 224 and 233), and instead of the cushion form, the caps are moulded. The north [Illustration: FIG. 237.--Kirkwall Cathedral. South Aisle of Nave.]