The only important alteration made in the original plans was the addition, in the 14th century, of chapels between the buttresses and flying-buttresses of the nave.
The Cathedral is built of grey limestone, on foundations 26 feet thick.
West Façade
The upper portion, consisting of two towers of unequal height, finished in different styles, belongs to the 14th century. The north tower, which is the higher, contains the great bells. The openings are decorated with statues of the Apostles, which have been either restored or renewed.
The upper storey of the south tower contains two bays with openings surmounted by gables. It is terminated by a pointed roof with a dormer-window and lead spikes. A gallery, called the ringers’ gallery, with covered arcades surmounted by pinnacles and turrets, connects the two towers.
Below this gallery is the great rose-window, of which the frame-work only belongs to the 13th century. The mullions are in the Flamboyant style. Below, running the whole length of the façade, are two superposed galleries.