This article examines the creative process of Diatope , a multimedia project created by Iannis Xenakis in 1978 for the inauguration of the Centre Pompidou in Paris, utilizing analytical research of sources found in several archives. By interpreting Xenakis's sketches and plans, the article elucidates for the first time the spatialization of La Légende d'Eer , the music featured in the Diatope . The findings of the research underline the importance of graphic and geometric representation for understanding Xenakis's thinking, and they highlight the continuity and evolution of his theory and practice over time. Furthermore, the research findings present the means by which this key work of electroacoustic music might be spatialized today, now that the original space of the Diatope no longer exists.