At the end of 1749, Madame de Pompadour got, instead of the Princesses of France, the apartment left by the Penthièvres; it is located on the ground floor in the northern parterre, downstairs a part of the big royal apartment.
It sanctions a new step in the mistresss life, who transformed herself from a lover into a friend and adviser, like Madame de Maintenon did for Louis XIV.
The responsibility of its restoration fell on Le Normant de Tournehem, general manager of the Buildings; he entrusted this task to the controller of the castle, Charles Lécuyer.
Several projects were prepared; one, dated 11th March 1750 on the front, got the marquises approval and the consent of the Prime Architect, A.J. Gabriel, on the 6th May. It was carried out according to the transformations indicated with red ink.
The notes or added papers correspond to the different levels: the decoration (corridors furnished with wardrobes, bathrooms, linen, servants rooms) occupied the whole castle height; at the extremities of the series of apartments, the first mezzanines were reserved for Doctor Quesnay and for Madame du Hausset.
In the marquises room you can notice a hesitation in the position of the bed, decorated with graphite; it was placed in a niche in front of the windows; you can see the winding staircase, that Louis XV went down unexpectedly; next, the enamelled red back room where the Prince of Croy were surprised several times in conversation with Jeanne Antoinette.
The works, entrusted to the usual teams of the Royal Buildings, lasted about a year, as the main craftsmen were the same already working in Bellevue, where they were performing miracles of speed. During the absence of the marquise, her friend Monsieur de Gontaut visited the building yard and accounted for it.
She was not able to move there until the spring of 1751.