Fixed, written music sometimes leaves room for improvisation. Whether in jazz, with its proposed themes, then the free fields offered to instrumentalists, or in contemporary music, where the open works proposed sketched out framework-free areas in which musicians could free themselves from the written word. In "Black Museum", improvisation was the source of the written word, of the composition. Composer Bruno Letort is no stranger to crossing genres, having written numerous contemporary works for orchestra, ensemble or soloist. While orchestrating "Multitude", Stromae's latest album (Victoire de la musique 2023), proposed to the cream of the improvisation world, notably American, to try this unique experiment of making improvisation the first stone of a composition for large instrumental ensemble. The rule was simple: improvise on a metronome, with no other constraints, neither rhythmic nor harmonic; simply play freely. Laurie Anderson, David Krakauer, Evan Ziporyn, David Torn, Mile Ladd, Régïs Boulard and David Linx, among others, were enthusiastic about the project and the first recorded elements, and agreed to embark on this astonishing, subtle marriage of the written word and free form. "Black Museum" explores the most unexpected sounds of orchestral playing and the most surprising harmonic and rhythmic constructions.