town, capital (since 1964) of Val-d'Oise departement, Paris region, northern France, on the right bank of the Oise River, northwest of Paris. In 1966 it became an episcopal see, and its cathedral, formerly Saint-Maclou Church, dates from the 12th century. It has a Flamboyant Gothic facade and a tower with a Renaissance dome. The double northern aisle is a Renaissance masterpiece. Pontoise was acquired by Philip I in 1064 and became the capital of the French Vexin region. It played a conspicuous part in the Hundred Years' War (1337-1453) and was twice in English hands in the first half of the 15th century. The Parliament of Paris met there several times in the 16th and 17th centuries. It was occupied by the Germans in 1870-71 and was damaged in World War II. Metallurgical and chemical industries form part of the town's economic base. Pop. (1990) 28,463.
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