Pontoise () is a commune in the northwestern suburbs of Paris, France. It is located from the centre of Paris, in the "new town" of Cergy-Pontoise. Administration 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 in 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. Sister cities The city of Pontoise has three sister city relationships with: Böblingen, Germany since 1956 Sevenoaks, United Kingdom since 1964 Geleen, Netherlands since 1962 Security Known for being a violent city in the late 20th century, with a criminal rate of 137.62 incidents per 1000 inhabitants, Cergy-Pontoise has enjoyed a significant decrease in violence in the first decade of the 21st century. By 2008, the rate had declined to 99.87, although this is still considered high. That rate has continued to decline in the second decade. History Pontoise is the historical capital of the Vexin français. Its foundation dates from Roman times (Pontisara). At that time, the rock peak overhanging the river Oise supported the defense of the fort 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. It is also known to many people as the birthplace of the alchemist Nicholas Flamel. With an over 2,000 year legacy, Pontoise still has vestiges of the past, such as medieval lanes, convents, churches and museums, and was awarded the "City of Art and History Label" in 2006. The impressionist painter Camille Pissarro made it famous through many paintings which are present nowadays in the most famous art galleries in the world. Climate Pontoise has a oceanic climate (Köppen climate classification Cfb). The average annual temperature in Pontoise is . The average annual rainfall is with December as the wettest month. The temperatures are highest on average in July, at around , and lowest in January, at around . The highest temperature ever recorded in Pontoise was on 1 July 2015; the coldest temperature ever recorded was on 1 January 1997. Demographics Immigration Transport Pontoise is served by Pontoise station, a terminus on