In the Fourteenth Century the large window in the north transept and the west windows of the nave were added. Then the cloisters were built and several halls. The refectory was turned into a library in 1661-1684. The central tower was repaired and rebuilt in the Fifteenth Century. Wyatt, who had charge of the restorations in 1796, destroyed the fine Norman Chapter-House (built in 1133-1140), rebuilt the turrets on the Chapel of the Nine Altars and placed a window of his own design in the east end, removing for the purpose the great Early English window. The original glass was also taken out and piled up in baskets. After much had been stolen the remainder was locked up in the Galilee. Some of it was inserted in the great round window. Wyatt came very near destroying the Galilee Chapel so that he could open the west doorway; but he was fortunately stopped. The chief restorations of late years have been those of 1870-1876, when the new choir-screen and pulpit were erected, the choir-stalls replaced and the floor of the choir paved with marble mosaic. From the large open space between the Cathedral and Castle, known as the Palace Green, we gain a fine view of the northern side of the building; the tall central tower and transept with its splendid window (1362) (The Four Doctors of the Church); and the north aisle to the Chapel of the Nine Altars that completes the eastern end. From this side we can study the towers to advantage. The two square, solid western towers date from Norman time; but the Norman work ends at the roof of the nave; then begins what is probably work of the Thirteenth Century. Here we have four stories ornamented with arcading, blind and open. The first and third have pointed arches, and the second and fourth round arches. The open parapets and pinnacles were added at the end of the Eighteenth Century. The =Central Tower= dates from about 1474, replacing an older tower that had been condemned. The belfry had been struck by lightning in 1429. The tower consists of two stories separated by a narrow gallery with a pierced and embattled parapet. This is called the Bell Ringers’ Gallery. The windows are arranged in pairs surmounted by ogee label moldings, crocketed and ornamented with finials. The tower is finished with an open-worked parapet, and at each corner are buttresses with canopied niches containing figures. We walk eastward to gain a nearer view of the Chapel of the Nine Altars with the Early Decorated window and turrets crowned with pyramids. We particularly want to see on the north-west turret the panel of the =Dun Cow=, a modern reproduction of an ancient work, commemorating the legend.