The Château Mont-Royal is a French chateau in La Chapelle-en-Serval, Oise, built for Fernand Halphen by the architect Guillaume Tronchet.
It was to offer his wife a view which enchanted her, he said, that Fernand Halphen bought the house at la Chapelle-en-Serval, near Chantilly (Oise) and decided in 1908 to erect a country house in a wooded valley there, which became known as the Château Mont-Royal. After having rejected the project with the Anglo-Norman style of the architect René Sergent, then the first project of a mediaeval style of the architect Guillaume Tronchet (drawings in the Musée d'Orsay), Halphen chose Tronchet's second plan, of a château celebrating hunting on the outside and music on the inside. Constructed from 1907 to 1911, the château (today transformed into a hotel) was a great architectural success. Under the façades, the bas-reliefs made by G. Gardet celebrate the pleasures of the hunt. The interior includes, notably, a theatre, a replica of that of the Opéra-Comique.