The Aisne department is located in the northern region of France and is part of the Hauts-de-France administrative region. It is the 11th most populous department in France, with a population of 535, 000 people. The department is named after the Aisne River, which runs through it. The department is known for its historical sites, such as the Château de Coucy and the Château de Laon. It is also home to the Chemin des Dames, a World War I battlefield.