The great central tower was erected between 1400 and 1423. Hitherto there had been the Early English tower of the elder John Romeyn, supported by Norman piers which, perhaps, had received a partial casing of Early English stonework. These piers were afterwards recased, not simultaneously, but as the arches between them were erected, in the following manner:-- Taking the south-western pier for an example: when the present nave was begun, the western face of the pier was cased with masonry, so that three parts still remained Norman; when the Decorated arch[1] in the transept was erected south of it, it received a further Decorated casing on its south side; when the central tower was built, its northern and eastern faces were cased with Perpendicular masonry: so, in the case of the north and south-eastern piers, their eastern faces were completely cased when the choir was built, their western only when the tower was in course of erection. To this day it may be seen that there is no bond between the different periods of masonry, and that the courses are at different levels. [1] For the explanation of the erection of this Decorated arch, see the architectural account of the transepts. The piers were probably completely recased by 1409. [Illustration: THE EAST END. From Britton.] Nothing is known of the elder Romeyn's tower, or the manner in which the present one replaced it. A great part of the new work has been attributed to Walter Skirlawe, Bishop of Durham. It will be seen it is of the same character as the lower part of the central tower at Durham. It has never been finished, as the corners and the condition of the masonry at the top still show, but it is impossible to say whether it was intended to receive another storey, and if so, of what character that other storey was to be. At one time, as may be seen in old engravings, it had a turret in one corner, 24 feet high; this was probably destroyed in the last century. The south-west bell tower was built probably between 1433 and 1447, the north-west between 1470 and 1474. They are thus both Perpendicular in style. At the end of the fifteenth century, therefore, the minster as we now see it was fully built. Since that date it has suffered no changes of importance, and the record is only one of occasional damage from fires or fanaticism, and of necessary restorations. The minster suffered to a certain extent at the restoration, and in a less degree at the hands of the Puritans. In 1734 the nave was repaved. Several tombs were found when the old pavement was removed, and relics taken from them and deposited with the other treasures of the minster.