As we look at the South Transept facade, the beholder perhaps needs to be reminded that this entire facade was not there in the 12th century when the cathedral was first built. The surface of the building has been pushed outwards a bay in the 13th century when the chapels were added, so that what we see belongs entirely to the 1260s and is associated with the work of the most famous Gothic master mason Pierre de Montreuil. Pierre de Montreuil, the I. M. Pei of Gothic architecture, was master of the works of Notre-Dame of Paris in the 1260s. He died in 1267 and was buried in his chapel of Saint Germain des Prés. Running along the exterior base of the South Transept facade is an inscription dated 1258 that records the agency of the master mason Jean de Chelles. Jean de Chelles was the predecessor of the famous Pierre de Montreuil.