In the western part, the nave and the transept, the walls up to the top of the storey of galleries are remainders of the Early Romanesque basilica. The Gothic modernization was begun ind the west and proceeded eastward. Most of the windows and the western portal were enlarged in Gothic style, but the vaults of the aisles of the nave are still of Romanesque type. Relics of the Romanesque walls of the choir, including a bank of stone, can be seen below the arcades around the choir. The outer walls of the ambulatory are originally Gothic, and so are the vaults of the ambulatory. Many details inside the church suggest that the builders followed the example of Laon Cathedral, the construction of which had been started one or two decades before the Gothic relaunch of St George collegial church in Limburg.