Then it was determined to have a large eastern Lady chapel. Not to interfere with the services, this was probably built completely detached from the cathedral, as at Lichfield and elsewhere. When it was finished the Norman apse would be pulled down, and the Lady chapel joined on to the presbytery. Two chapels also were built, one on each side of the westernmost bay of the new Lady chapel. This work was probably done _c._ 1280. The next step was to continue the northern of these chapels eastward, so as to provide the presbytery with a northern aisle of two bays, and to pierce the north wall of the presbytery with a couple of arches. No doubt they would have liked a couple of arches in the southern wall; but unfortunately the bay of the aisle on the other side of it had been vaulted, and so only one arch was inserted, leaving as much wall as possible to support the vault. Under this arch the sedilia were placed. Soon afterwards the outer wall of the south aisle of the presbytery was rebuilt. But the presbytery was very dark, having no windows to the east, and being much blocked on the south side by the sedilia and by the mass of Norman walling which it had been necessary to retain. So it received a clerestory and very large aisle-windows. Nor were the nave and choir well lighted. In the clerestory and west front they had only lancet windows; and, if the low Norman aisles still remained, they could contain but very diminutive windows. There was nothing for it but to rebuild the whole of the eight bays of each aisle. This rebuilding probably went on between 1315 and 1360, for the windows have ogee dripstones and ogee patterns in the tracery. When the aisles had been rebuilt the whole cathedral had been reconstructed, with the exception of two Norman doorways and two or three Norman arches in the presbytery. To us it may seem a topsy-turvy mode of procedure to first rebuild the inside—the pier-arcade and clerestory—of a church, and the outside walls afterwards; but it is the mode of procedure adopted in scores of parish churches, even the humblest. One constantly finds the aisles, as at Wakefield, of later date than the pier-arcade, and that pier-arcade a rebuilding of something older. After this great reconstruction, first of the interior, then of the exterior, there remained only to complete the west front. The south-west tower seems to have become ruinous or to have collapsed, and the materials of it helped to build a new north-west tower erected at the cost of Jasper Tudor, uncle of Henry VII. Then came the Reformation; and the south-west tower was not rebuilt till the present century. Since 1843 nave, choir, and presbytery have been almost wholly rebuilt. St. Asaph. [Illustration: NAVE, LOOKING EAST.]