Pléven is a former commune in the Côtes-d'Armor department of Brittany in northwestern France, 70 km north west of Rennes. It was merged …Pléven is a former commune in the Côtes-d'Armor department of Brittany in northwestern France, 70 km north west of Rennes. It was merged with Pluduno to form Val-d'Arguenon on 1 January 2025. The Arguenon river flows through the commune.