<P> Significant among Louis XV 's contributions to Versailles were the petit appartement du roi ; the appartements de Mesdames , the appartement du dauphin , the appartement de la dauphine on the ground floor ; and the two private apartments of Louis XV -- petit appartement du roi au deuxième étage ( later transformed into the appartement de Madame du Barry ) and the petit appartement du roi au troisième étage -- on the second and third floors of the palace . The crowning achievements of Louis XV 's reign were the construction of the Opéra and the Petit Trianon . </P>
who expanded the palace of versailles to its present size
Louis XV