Notre-Dame lies at the eastern end of the Île de la Cité and was built on the ruins of two earlier churches, which were themselves predated by a Gallo-Roman temple dedicated to Jupiter. The cathedral was initiated by Maurice de Sully, bishop of Paris, who about 1160 conceived the idea of converting into a single building, on a larger scale, the ruins of the two earlier basilicas. The foundation stone was laid by Pope Alexander III in 1163, and the high altar was consecrated in 1189. The choir, the western facade, and the nave were completed by 1250, and porches, chapels, and other embellishments were added over the next 100 years. (source:http://www.confiduss.com/en/jurisdictions/france/ )
