This book tells the singular story of the meeting between a famous seamstress between the wars, Jeanne Lanvin, and a designer particularly sought after at that time, Armand Albert Rateau. From this collaboration came the creation of the Lanvin boutiques between 1920 and 1925, the decorations of the hotel of the seamstress and its two country houses, the Daunou theater and the astonishing Pavillon de l'Elegance, designed to house the creations of the most famous representatives of haute couture at the International Exhibition of Decorative Arts of 1925. We discover how much the worlds of the two creators are close by their attachment to a past they reinterpret with great freedom. The precious embroidery of one meets the sophisticated motifs of the other, elaborated in the same world where the imagination holds the first place. Rich in unpublished information, this book brings to life the extraordinary creative impetus that reigned after the First World War in the field of decoration as