Boulogne-sur-Mer Castle, locally known as Château de Boulogne-sur-Mer or simply the Château Comtal (Count's Castle), lies in the center of the city of Boulogne-sur-Mer in the Pas-de-Calais department in the Nord-Pas-de-Calais region in France.
Between 1227 and 1231 Philip I, Count of Boulogne and son of Philip II of France, restored the fortifications of Boulogne’s medieval upper town, building on top of the ancient Roman city walls. The castle was built in the eastern corner of the medieval city and thus became an integral part of its defenses. Philip I also built Hardelot Castle to a rather similiar plan; a more or less circular castle with projecting circular towers but no keep.
Between 1394 and 1416 the castle underwent major alterations by John, Duke of Berry. The earldom of Boulogne became the property of Burgundy and was finally united with the Crown by Louis XI in 1478.
In the first half of the 16th century, under Francis I of France, Boulogne-sur-Mer castle was adapted to the advancements in artillery and a kind of casemate was build against its field facing facade. In 1544 the upper town and the castle were taken by Henry VIII of England. Boulogne remained under English control until 1550 when it was bought back by the Henri II, King of France.
At the end of the 16th century, Vauban, the famous military engineer, proposed modernising the fortifications of Boulogne-sur-Mer to Louis XIV of France. Louis however thought the costs to high and, also because the castle and city had lost their strategic importance, ordered the demolition of its fortifications in 1689. This, however, was prevented by the local population.
In 1767, after a period of abandonment, Boulogne-sur Mer Castle became a barracks. After World War II it was also used as a prison. In 1974 it became owned by the town council, who opened a museum in it in 1988.
At present the castle houses a museum. The museum however is just a regular world history museum and not related to the castle's history. This is a beautiful castle in a very nice old town.