The western towers opened with arches into the north, south, and central aisles, but only the north tower retains its massive pier and arches, while of the south tower nothing but the foundation of the pier exists. The south wall of the transept is externally plain, the upper part being visible above the dormitory roof. The facade has two plain lancet windows, one shorter than the other, and above them is a large wheel window. The interior of the transept is a very grand design in the early pointed style.[443] Beneath the splayed lancets there is a round arched open arcade, with a passage behind it, and beneath this, two tiers of wall arcades with pointed arches, the central arcade being very acutely pointed, the lower one not so decidedly, and with trefoil cusps in the arches. A staircase in the S.E. angle of the transept gave access to the dormitory by the door, seen built up on the outside.[444] This staircase also leads to the various passages in the thickness of the walls, and the church doorway leading to this stair is round arched and ranges with the lower pointed arcade. The lower arcade of the south end is continued along the west wall, and above this rise two widely-splayed windows. All the lofty south transept windows have passages on two floors, and the transepts had chapels on the east side. "The respond of the great arcade against the south wall is beautiful in detail. Above this there exist fragments of the responds of the triforium story and the clerestory. All the above features of this part of the abbey point plainly to its having some lingering remains of transition style, retaining, as it does, some round arches along with the general features of the design."[445] The vestry or sacristy was built by Abbot Walter Painter between 1411 and 1433, and is a two-storied building, the ground floor having a groined ceiling, still entire, and the upper room being roofless. Its features are of fifteenth-century work, and the building is in good preservation.