The Chateau de Boulogne-sur-Mer is a castle in the French seaport of Boulogne-sur-Mer, in the Pas-de-Calais departement. It houses the Boulogne museum. The castle was built in the 13th century by Philippe Hurepel (1180-1234), count of Boulogne and son of Philip II of France. Following the death of his half-brother, king Louis VIII after a short three-year reign, Hurepel was one of the leaders of a rebellion against the regent, Blanche de Castille, mother of the minor Louis IX. He constructed castles at Calais and Hardelot and refortified Boulogne.
The castle is built in the eastern corner of the medieval walls surrounding the Haute Ville (literally, high town - the part of Bologne on the hill). The walls themselves were reconstructed by Hurepel. The eastern part of the castle was built over a corner of the Roman wall, parts of which are still visible in the basement. Housing together the political, legal and economic powers of the time, it was also a residential and defensive site.
Various modifications have taken place. Major alterations were carried out by the duc de Berry between 1394 et 1416. The horse shoe shape (barracks, arsenal) was completed around 1567. After being adapted because of developments in artillery during the 16th century, it lost some of its medieval character. In 1767, it became a barracks and, after World War II, it also housed a prison. In 1974, the town council took over ownership of the castle and decided to install its museum collections.