Madame Adélaïde (1732-1800) was one of Louis XV’s children. As such, she was a “Daughter of France,” and was accorded a truly royal apartment in the main block of the Château.
Her apartment adjoins that of her younger sister, Mme Victoire (1733-1799). I previously described Mme Victoire’s apartment in an early post on this blog: http://versaillescentury.com/2016/09/22/versailles-mme-victoires-apartment/#more-304
The 2 sisters were the last of Louis XV’s offspring still alive and living in the Château towards the end of the reign of their nephew, Louis XVI. The latter also gave them the Château de Bellevue, and, unprecedentedly, the joint dukedom of Lauzun. The layout of the rooms today is as it was arranged for the sisters in the 1780s.