Cergy () is a commune in the French department of Val-d'Oise, in northwestern suburbs of Paris. It is located 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 (capital) of the Val-d'Oise département, the préfecture building and administration, as well as the department council (conseil général), 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. Name The name Cergy comes from Medieval Latin Sergiacum, meaning "estate of Sergius", a Gallo-Roman landowner. Administration Cergy is the chief town of two cantons: Cergy-1 and Cergy-2. Twin towns and sister cities Columbia, Maryland, United States. Erkrath, Germany. Liaoyang, People's Republic of China. Porto Novo, Benin. Tres Cantos, Spain West Lancashire, United Kingdom. Cergy is also informally twinned with a village in Palestine and a village in Senegal. Demographics When Cergy was selected to become the center of a "new town", it was only a village. The commune had only 2,895 inhabitants in 1968. It then started to develop very quickly, exceeding 10,000 inhabitants in the mid-1970s and then 20,000 in the early-1980s. It is in this decade that its growth was most spectacular, since the city exceeded 48,000 inhabitants in 1990. The increase continued since, but at a notably slower pace, to reach 54,500 at 2004 estimates. However, in December 2001, the commune lost a portion of its territory (net with a 1999 population of 62 persons) to the adjacent commune of Courdimanche. The official census figures have thus been revised downward from the 1999 official 54,781 to 54,719, and the land area from to 11.65 km2. Immigration Port Cergy Port Cergy is a marina on the River Oise at pk 9. The site comprises both housing and recreational yachts as well as a boating school. The marina can hold 103 ships ranging 5 to 22m long and. The northern part of the site is reserved for restaurants and shops and have been built around a small bain. Ham Ham is a small village to the south of Cergy. The village used to be part of the Sergentery and then commune of Neuville-sur-Oise but has since been amalgamated in the commune of Cergy. On its territory