Cergy

Cergy is a commune in the French department of Val-d'Oise, in northwestern suburbs of Paris. It is located 27.8 km from the centre of Paris, in the "new town" of Cergy-Pontoise, created in the 1960s, of which it is the central and most populated commune.

Although neighbouring Pontoise is the official préfecture of the Val-d'Oise département, the préfecture building and administration, as well as the department council, are located inside the commune of Cergy, which is regarded as the de facto capital of Val-d'Oise. The sous-préfecture building and administration, on the other hand, are located inside the commune of Pontoise.