Both the Palais Bourbon and the Hôtel de Lassay were in the Italian style, with roofs hidden by balustrades and invisible from street level. The Palais Bourbon was in a U-shape. The main building was parallel to the Seine, with two wings enclosing a courtyard. The entrance to the courtyard and building was on the Rue de la Université. The entrance to the courtyard had an ornate archway, flanked by two pavilions. The Hôtel de Lassay was rectangular, and more modest in size. The two buildings had identical facades facing the Seine. The facades featured alternating columns and windows, and decoration on the themes of the seasons, the elements, and, fitting for the daughter of the Sun King, about Apollo. The space between the buildings, and between the buildings and the Seine, was filled with gardens. In addition to the large reception rooms, the interior of the house had many small salons which could be arranged for a variety of purposes. It also had a novelty for buildings of the period; corridors, so one could pass through the building without walking through the rooms. None of the original apartments of the Duchess survive; they were demolished in the subsequent remodelings. The Duchesse de Bourbon died in 1743, and De Lassay died in 1750. The Palace was purchased by Louis XV, who seems to have wished to include it in the plan of the new place Royale (now the Place de la Concorde) which he was building on the other side of the river. But in 1756 he sold it to grandson of the Duchess, Louis Joseph, Prince of Condé, who had been a military hero in the just-concluded Seven Years' War. The Prince decided to largely rebuild it, turning it from a country house into a monumental palace, in the new classical revival style. With this end in mind, in 1768 he purchased the neighboring Hôtel de Lassay, and planned to make the two buildings into one. A new plan was drawn by Marie-Joseph Peyre, whose style was based on archeological studies of ancient Rome and Greece. Peyre's other neoclassical works included the Odéon Theater. Several different architects were engaged in the project, including for Jacques-Germain Soufflot, Bellisard and Charpentier.