On 16 July 1819, the estate was acquired by the duc d’Orléans, the future Louis-Philippe I, in exchange for écuries called “de Chartres”, situated on rue Saint-Thomas du Louvre, which he owned. He appointed Henri Antoine Jacques as head gardener and had Pierre-François-Léonard Fontaine transform the château. He also expanded the estate by acquiring 7 islets in the middle of the Seine and linking them to the château by an iron-wire bridge so as to be able to reach the island now known as the île d’Amour (Isle of Love). To that island he transferred the “Temple of Love” which his father Philippe-Égalité, when duc de Chartres, had built in 1774 in Paris’s Parc Monceau (also known as the “Folie de Chartres”).
The House of Orléans especially liked the château de Neuilly, using it as their summer residence – with its long, low buildings, it provided a discretion suitable to this bourgeoise monarchy. The parc, mostly wooded, was surrounded by a high fortified wall which kept out prying eyes. It was the birthplace of three of Louis-Philippe’s children – Clémentine, François and Antoine.