We now come to the period in which the "two great and famous productions of the fourteenth century--the two special objects of pride which our Cathedral boasts--the Lady Chapel and the central Octagon, with the three adjoining bays eastward,"[8] were erected; "each work is of the highest and of undisputed merit, and forms a most marked feature in the building;"[9] affording most admirable specimens of the Decorated English style. In 1321 the foundation stone of the vast and magnificent Lady Chapel was laid by Alan de Walsingham, then sub-prior, in the time of Bishop Hotham (1316-1337), the work was continued under Bishop Montacute (1337-1345), and finished in 1349, under Bishop L'Isle (1345-1362). In the year following the commencement of this work the fall of the great central Tower took place, ruining the adjoining bays all round, and especially those of the Norman Presbytery. This catastrophe was not altogether unexpected, for the monks had discontinued the use of the Choir and held their services in St. Catherine's Chapel, in the western part of the Cathedral. The Tower fell with such noise and violence as "to make the whole city to tremble, and to cause men to think that an earthquake had taken place." The work of rebuilding was soon undertaken, and under the skilful directions of the same Alan de Walsingham (who was doubtless the architect of both these erections,) the grand work was accomplished; the stone-work of the Octagon was finished (if indeed it ever was quite finished) in 1328, and the woodwork and roof about 1342. The plan of the Octagon included in its area one bay on each of its four sides. The expense of rebuilding the three bays on the eastern side was defrayed by a sum of money left by Bishop Hotham. [Footnote 8: Ibid.] [Footnote 9: Ibid.] The spire erected on the western Tower by Bishop Northwold was taken down in the latter part of the fourteenth century, and was replaced by an octagonal story, flanked with turrets, in the Decorated style, above which a spire was again placed. This was an injudicious step, and has been thought to have been the primary cause of the ruin of the north-western Transept, the great additional weight being more than the four supporting arches (which were lofty) were intended to bear. Of the period when the Transept fell, or was taken down, we have no record; but the character of the buttress on the site of the western wall shows that it must have been at an early period, probably about A.D. 1400, as the strengthening arches placed within the original ones appear to have been erected a few years after.