The town of Cergy is situated near the confluence of the Oise and the Seine, at the gateway to the French Vexin .
When Cergy was chosen to become the centre of the new agglomeration it was as yet no more than a village located on the Oise.
By the river there were grazing pastures and fields for market gardening; on the middle of the slope stood the village and above that the sunny hillsides, an ideal place for wine growing, which was in fact the principal activity until the end of the 19th Century. Rather than grafting the new town on to the existing core, the urban planners chose to create new centres from scratch, and away from it, thus making it possible to preserve the old villages. In about fifty years the new town has been built from East to West, from the outskirts of Pontoise to the Hauts-de-Cergy plateau. Cergy is thus structured like an amphitheatre, in which districts of varying architectural forms combine harmoniously with green, natural spaces. Due to its situation and importance Cergy has become the heart of the new town within the Cergy-Pontoise agglomeration.