Beginning in 1546, after returning from his captivity in Spain, King Francis I of France employed architect Pierre Lescot and sculptor Jean Goujon to remove the keep and modernize into a Renaissance style palace. Lescot had previously worked on the châteaux of the Loire Valley and was adopted as the project architect. The new plan consisted of a square courtyard, with the main wing separated by a central staircase, and the two wings of the sides comprising a floor. Lescot added a ceiling to King Henry II's bedroom (Pavillon du Roi) that departed from the traditional beamed style, and installed the Salle des Caryatides, which featured sculpted caryatids based on Greek and Roman works. Art historian Anthony Blunt refers to Lescot's work "as a form of French classicism, having its own principles and its own harmony". Francis acquired what would become the nucleus of the Louvre's holdings; his acquisitions included Leonardo da Vinci's Mona Lisa