Before completing the description of the choir it may be pointed out that the north wall presents some peculiarities. It has already been mentioned that the wall is solid, having in the lower part no openings to the side aisle, except that leading to the chapter house. It would appear, however, that this was not always the case, as there are traces in the side next the aisle of a window which has been built up. The wall is also in its lower part built with rubble, and it may be conjectured that this wall was part of the original choir of the Church of the Holy Trinity, which had been begun when the see of the bishop was transferred to the site of that church. Another peculiarity is that the windows in the triforium of the western portion are smaller than those of the rest of the choir. Possibly the western aisle, which was cut off from the choir by a solid wall, was used as the sacristy. [Illustration: FIG. 548.--Elgin Cathedral. South Aisle of Choir, or Lady Chapel.] The transepts, like the nave, have been greatly destroyed, and the [Illustration: FIG. 549.--Elgin Cathedral. Western Doorway.] chapels, if any such formerly existed on the east side of the transept (which, however, does not seem to have been the case), have now entirely disappeared. The south wall of the south transept (see Fig. 547) is especially interesting from its containing the oldest architecture in the cathedral. The various features all show that it belongs to the period of transition from Norman to first pointed, which in Scotland occurred about the beginning of the thirteenth century. The forms of the buttresses and the introduction of the pointed lancet windows below the circular arches on the upper floor show that the first pointed style was making rapid progress, while the circular arches of the upper windows and the Norman ornaments inserted in the pointed doorway of the south transept show some lingering remains of the earlier style. Perhaps the transition in this northern region may have taken place at a later period than in the south; and, to judge from the transition style here employed, which in a more southern situation would indicate a date about 1200, this part of the structure may have been erected immediately after the foundation of the cathedral in 1224; or the transept may have formed part of the original Church of the Holy Trinity, which was superseded by the cathedral. The transept would be of great size for an ordinary church, but would accord well with the dimensions of an edifice intended for a cathedral.