The Mount-Royal castle is a built castle with Vault-in-Serval (Oise) by the architect Guillaume Tronchet on behalf of the type-setter Fernand Halphen.

After having rejected the project of Anglo-Norman style of the architect Rene Sergeant, then a first project of medieval style (drawings with the Museum of Orsay), the silent partner fixed his choice on the second project of Guillaume Tronchet: a castle of style Louis XVI celebrating hunting outside and the music inside.

On the frontages, low-reliefs which had with G. Gardet celebrate the pleasures of hunting. The interior includes/understands in particular a theater, retorts that of the Op3era Comique.

Built of 1907 to 1911, the castle is a great architectural success. During the Second world war, the castle is plundered and emptied of its furniture. In 1989, J.P.Hermier buys it with the descendants of Fernand Halphen and transforms it into hotel, which opens its doors in 1990. In June 1992, the group of the Concorde hotels acquires the whole of the property.