Duke of Valentinois (; ) is a title of nobility, originally in the French peerage. It is currently one of the many hereditary titles claimed by the Prince of Monaco despite its extinction in French law in 1949. Though it originally indicated administrative control of the Duchy of Valentinois, based around the city of Valence, the duchy has since become part of France, making the title simply one of courtesy. It has been created at least four times: on August 17, 1498, for Cesare Borgia, in 1548 for Diane of Poitiers, in 1642 for Prince Honoré II of Monaco, and most recently in 1715 for Prince Jacques I of Monaco. Counts of Valentinois First creation King Louis XII of France and Naples created Cesare Borgia Duke of Valentinois in 1498. Both the Italianized form of this title and his previous appointment as Cardinal of Valencia led to his commonly used nickname: "Il Valentino". After Cesare's death, his daughter Louise Borgia (15001553) did not become Duchess suo jure due to the male-only succession of the title, but was instead styled "Dame Valentinois", titular Duchess of Romagna and Countess of Diois. Second creation King Henry II of France created his mistress Diane de Poitiers Duchess of Valentinois in 1548. She was the only suo jure Duchess and her title was destinated to end after her death, due to the Salic law commonly used among French nobility. Third creation King Louis XIII of France created the title by letters patent, signed in May 1642 and registered on 18 July 1642, as a conglomeration of several estates in the French province of Dauphiné which he had previously given to Honoré II, Prince of Monaco. The first person to hold the title was Honoré II, Prince of Monaco, reigning Prince at the time of its creation; on his death it passed to his grandson Louis I, and thence to Louis's son Antoine. However, since the title's inheritance was restricted to male heirs, and because Antoine had only daughters and no sons, it was due to pass his brother, François-Honoré Grimaldi, but became extinct on 22 July 1715 when François-Honoré forfeited his right to succeed Antoine. Fourth creation On 20 October 1715, Antoine's eldest daughter and heiress Louise-Hippolyte married Jacques-François de Goyon-Matignon, who had signed a contract on 5 September 1715 by which he was obliged to take the surname Grimaldi. King Louis XV of France