<P> Numerous architects worked on the site over the period of construction, which is evident from the differing styles at different heights of the west front and towers . Between 1210 and 1220, the fourth architect oversaw the construction of the level with the rose window and the great halls beneath the towers . </P> <P> The most significant change in design came in the mid 13th century, when the transepts were remodeled in the latest Rayonnant style; in the late 1240s Jean de Chelles added a gabled portal to the north transept topped off by a spectacular rose window . Shortly afterwards (from 1258) Pierre de Montreuil executed a similar scheme on the southern transept . Both these transept portals were richly embellished with sculpture; the south portal features scenes from the lives of St Stephen and of various local saints, while the north portal featured the infancy of Christ and the story of Theophilus in the tympanum, with a highly influential statue of the Virgin and Child in the trumeau . </P> <Ul> <Li> 1160 Maurice de Sully (named Bishop of Paris) orders the original cathedral demolished . </Li> <Li> 1163 Cornerstone laid for Notre - Dame de Paris; construction begins . </Li> <Li> 1182 Apse and choir completed . </Li> <Li> 1196 Bishop Maurice de Sully dies . </Li> <Li> c. 1200 Work begins on western facade . </Li> <Li> 1208 Bishop Eudes de Sully dies . Nave vaults nearing completion . </Li> <Li> 1225 Western facade completed . </Li> <Li> 1250 Western towers and north rose window completed . </Li> <Li> c. 1245--1260s Transepts remodelled in the Rayonnant style by Jean de Chelles then Pierre de Montreuil </Li> <Li> 1250--1345 Remaining elements completed . </Li> </Ul> <Li> 1160 Maurice de Sully (named Bishop of Paris) orders the original cathedral demolished . </Li>

When was the cathedral of notre dame built
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