Pontoise is a commune in the northwestern suburbs of Paris, France. It is located 28.4 km. (17.6 miles) from the center of Paris, in the "new town" of Cergy-Pontoise.
Pontoise is the official préfecture (capital) of the Val-d'Oise département, although in reality the préfecture building and administration, as well as the department council (conseil général), are located inside the neighboring commune of Cergy, which is regarded as the de facto capital of Val-d'Oise.
Pontoise is also the seat of the Arrondissement of Pontoise. The sous-préfecture building and administration, unlike the préfecture, are located inside the commune of Pontoise.
Pontoise is the historical capital of the Vexin français. Its foundation dates from the Roman times (Pontisara). At that time, the rock piton overhanging the river Oise supported the defense of the ford which was on the Roman road, the Chaussée Jules César, between Lutetia (Paris) and Rotomagus (Rouen). The road still exists and is now part of the N14 from Paris to Rouen.
