The particularly sober front elevation brings out the simplicity of the pattern of pink stones. It is punctuated by a line of evenly spaced windows, arranged around an imposing carriage entrance in the Classical style. The decoration is limited to alternating broken and arched pediments, supported by classically inspired corbels.
The hôtel passed throught a number of different hands. In 1829, it was bought by Jean-Hugues Magnin, the grandfather of the collectors, who handed it on to his son Joseph (1824-1910) and his wife Pauline Belloncle. Their two children, Maurice and Jeanne, lived there as children, before moving to Paris when their father was summond there to take on important political responsibilities during the fall of the Second Empire. It was they who created the collection, installed it in the family home and bequeathed both to the State.
One major change, but carried out with respect for the unity of the whole, was the addition in 1851 of an upper storey, in Louis XV style, to the stables situated at the end of the courtyard. When the idea for a museum was first mooted, the renovation work to transform the former staff quarters into galleries was entrusted to Auguste Perret, architect of the Théâtre des Chmps-Elysées, who worked there from 1930 to 1931. He installed zenithal lighting in the former courtyard, and attempte to blend the new material of reinforced concrete with the mansion's classical architecture.