The Basilica of Notre-Dame de Boulogne is a minor basilica located in Boulogne-sur-Mer in the Pas-de-Calais département of northern France. The basilica was built between 1827 and 1875 on the site of Boulogne's medieval cathedral with its 101 metre high dome. The basilica is still known locally as the "cathedral", despite the present church never having held that status.