Equipped with a smartphone or a tablet, the visitor will observe the history of this unique place through a path of 3D animations, augmented reality and points of interest. It will be possible to explore the Cour d'Honneur, the galleries, a powder shop through different periods between the 16th and 19th centuries. The history of the site and the geopolitical context of the events of 1870-1871 are thus put forward for a captivating immersion within an impregnable Citadel.