 In the 15th century some modifications and embellishments were made to the castle by Isabeau of Bavaria, the wife of King Charles VI, but the medieval structure remained essentially intact until the reign of Francis I (1494–1547).He commissioned the architect Gilles Le Breton to build a palace in the new Renaissance style, recently imported from Italy.Le Breton preserved the old medieval "donjon", where the King's apartments were located, but incorporated it into the new Renaissance-style "Cour Ovale", or oval courtyard, built on the foundations of the old castle.