Assuming as I do that the external wall of the apse is as old as the end of the eleventh century, I think it nevertheless quite impossible that the chapels within it, in their present state, should be of the same early date. In general plan it is true that they are similar to those round the chevet of the abbey at Veruela,[173] the eastern chapels in the transepts being apsidal in both cases, and similarly planned in connection with those of the apse. The church of Veruela was completed by about the middle of the twelfth century, and is beyond all question earlier in style than the interior of Avila. The great beauty of the latter arises from the narrow, recessed aisle round the apse, the groining of which is carried on lofty and slender shafts, whilst the columns round the apse itself consist of a bold single column with three detached shafts on the side next the aisle. The groining throughout is extremely good, and, in the chapels, is carried on clustered shafts. A careful examination of the groining of the choir shows clearly how much the design of the church was altered during its progress, though it is certainly not an illustration of the advantage of such a course. The lines of the groining on the plan explain that it is planned with hardly any reference to the structure below: some of the groining shafts not being over the piers, and everything having been sacrificed by the architect of the triforium and clerestory in order to make all their bays equal in width both in the apse and in the side walls. East of the Crossing there is a narrow quadripartite bay of vaulting, then a sexpartite bay, and then those of the apse, and each of the three bays of the choir is thus made about equal to those of the apse, though the arches below are quite unequal. Externally all of them are supported by regularly arranged flying-buttresses, some of which must, I think, be supported on the cross-arches of the aisle in front of the chapels. The triforium is round-arched, of two horseshoe-headed lights divided by a shafted monial; and the clerestory is of round-headed broadish windows, with jamb-shafts and richly-chevroned arches. The flying-buttresses are all double, the lower arch abutting against the triforium, and the upper against the wall above the clerestory windows; and all appear to me to have been added after the original erection of the clerestory. The parapet here, as well as in the aisles, is battlemented, the battlements being finished with pyramidal copings of the common Moorish type. I should have observed that the passage round the town walls is connected with that round the aisle walls, and that the two levels of battlements in the latter are connected by occasional flights of stone steps.