During the Middle Ages the Boulogne forest massif in which the National Estate of Chambord is located was the property of the counts of Blois; in 1498, it became a crown property, a royal domain.
During the Middle Ages it extended from Mont-près-Chambord in the west to la Ferté-Saint-Cyr in the east. Its northern boundary ran parallel the somewhat distant Cosson river, while the southern confines of the massif were close to the course of the Beuvron river. In 1523, at the initiative of François I, the boundaries of the Chambord park were delineated in these ample confines. During his youthful sojourns in Romorantin in Blois, François I developed a passion for hunting. In 1515, when he became king of France, he decided to have his castle built in an immense park in the heart of the Boulogne forest massif and on the farmland north of the Cosson. Ideal hunting grounds were thenceforth at his disposal.