The Norman east end and the whole of the central area of the crossing are now entirely gone, but the architecture of the transepts survives in a virtually complete state, to give a good impression of how it would have looked. Massive walls pierced by Romanesque arches would have formed aisles running around all sides of the choir and transepts. Three tiers of archways rise from the arcaded aisles. Galleries with walkways could be used for liturgical processions, and above that is the Clerestory with a passage within the width of the wall.