In the 13th century, the castle was then a fortified enclosure of polygonal shape, in a context of fortification of the coast in the face of French, English and Flemish desires. In addition to its defensive function, the castle also constitutes a comfortable pleasure residence, where the counts of Boulogne reside, go hunting and feast.
In the 15th century, Picardy and the Côte d'Opale were attached to the Kingdom of France. Hardelot Castle then became a royal stronghold.
Having fallen into ruin, it was bought in the 19th century by several wealthy English owners, who successively undertook the work giving it its current appearance with this neo-Tudor architecture typical of British buildings.
The last of them, John Robinson Whitley acquired it in 1897. Industrialist and co-founder of Le Touquet-Paris-Plage, he wanted to found a new competing seaside resort, Hardelot-Plage in order to welcome the British and French Gentry. . In 1905 he created the Société Anonyme d'Hardelot and the castle became the central place for social life in the resort. In particular, he will start his golf course from one of the towers of the enclosure...
Now managed by the Department of Pas-de-Calais, the castle now houses the Entente Cordiale Cultural Center and has become a heritage site dedicated to culture, the arts and the history of Franco-British relations.