 In the current structure the original Norman arches survive principally under the central tower and on the north side of the nave.The arches in the rest of the building are Gothic, following medieval rebuilding and extensions, and Victorian era restoration.The Abbey was extended in the 1190s by Abbot John de Cella (also known as John of Wallingford) (1195–1214); as the number of monks grew from fifty to over a hundred, the Abbey church was extended westwards with three bays added to the nave.