Poissy, a town of northern France, in the department of Seine-et-Oise, 17 m. W.N.W. of Paris, on the railway from Paris to Rouen. Pop. (1906), 604 3. The church, supposed to have been built in the first half of the 12th century, and eventually restored under the direction of Viollet le Duc, is of special architectural interest, as affording one of the earliest and best examples of transition from the Romanesque to the Pointed style. The bridge of Poissy, a very ancient foundation, has been widened and modernized; of the mills which formerly bordered it one was known as Queen Blanche's. A statue of the painter J. L. E. Meissonier was erected in 1894, close to his house. Poissy supplied butchers' meat to Paris during six centuries, but in 1867 the market was removed to the metropolis. A handsome fountain stands in the old market-place. Distilling and the manufacture of chairs and flour-milling equipment are carried on and ragstone is quarried.
Poissy, the ancient Pinciacum, was the capital of the country of the Carnutes. In the time of Charlemagne it had a royal palace, where during the 9th century four national assemblies were held. Later it became a favourite residence of Blanche of Castille, and her son, afterwards St Louis, is supposed to have been born there. Philip the Fair gave the castle to the Dominicans, by whom it was completely transformed, and it was in the refectory of the abbey that the famous conference (see below) between the Roman Catholics and Protestants took place in 1561.
