At the beginning of autumn, hikers walking the trails of the Cotentin, between the granite hamlets and the iodized sea mists of the Cap de la Hague, often encounter a green hill covered with short grass and sometimes grazed by a few sheep. At first glance, nothing distinguishes this mound from the other reliefs in the region. Yet, under this peaceful meadow rest nearly 527,000 cubic meters of radioactive waste, inherited from a quarter of a century of French nuclear activity. Authorities estimate that the site will need to be monitored for three centuries, a duration that far exceeds the life expectancy of several future generations. The Manche Storage Center, located in Digulleville, received between 1969 and 1994 nearly 1,469,265 packages of radioactive waste, or approximately 527,225 cubic meters. A permanent cover, installed between 1991 and 1997, now covers the site and forms the hill visible today. Entered into active monitoring since 2003, the site will need to be monitored for approximately three centuries, potentially until 2269. The site is called the Manche Storage Center, located in the commune of Digulleville, a few cable lengths from the Hague reprocessing plant. It is simply the first French center for storing radioactive waste, put into service in 1969. Before this site was chosen, engineers had for a time considered using the dunes of Biville, a neighboring military property. It was finally a wetland called the "Haut Marais" that was chosen to host this particular installation. The center extends over about 15 hectares, but the core of the storage is concentrated on a very specific strip of land: 600 meters long, 300 meters wide and 10 meters high. It is this structure, now covered with soil and grass, that forms the famous hill seen by hikers. Under this vegetative cover rest approximately 1,469,265 packages of waste, representing a total volume of 527,225 cubic meters, according to the data of the Nuclear Safety Authority. Created by decree in June 1969 as basic nuclear installation number 66, the Manche Storage Center had a very specific mission: to accommodate low and medium activity short-lived waste, that is, waste whose radioactivity decreases significantly in less than 30 years. For twenty-five years, trucks have flowed toward Digulleville, depositing packages mainly from the French nuclear power production, which was then in full growth. This logistical ballet lasted until July 1994, the date at which the last packages were taken in charge by the center. The site had then reached its maximum capacity. It then took nearly six years, between 1991 and 1997, to install a permanent cover intended to permanently isolate the waste from the external environment. It is this protective layer, made of waterproof materials and then covered with topsoil, that gave rise to the hill known today. Once the cover was completed, the site entered into an active monitoring phase in January 2003. In practice, this means that teams regularly check the impermeability of the hill, the quality of groundwater around it, and the general evolution of the installation. A bit like a doctor who follows a patient on a very long term, without heavy intervention, but with constant vigilance. On the regulatory plane, the Manche Storage Center remains officially in the dismantling phase until the end of the installation of this permanent cover. A decision by the Nuclear Safety Authority still needs to specify the exact date of the definitive closure of the storage, as well as the minimum duration of the monitoring phase. According to current estimates, this monitoring period should last approximately three centuries, or a monitoring that could theoretically be extended until 2269. This discreet hill in the Cotentin is much more than a simple landform accident. It embodies the challenges posed by the management of radioactive waste: how to durably isolate a dangerous material while preserving, on time scales that exceed human understanding, the memory of what is buried beneath our feet? Future generations will have to inherit not only the site itself, but also precise knowledge of its contents and the precautions to take. At a time when the debate on the future of French energy remains lively, this discreet nuclear cemetery, covered with grass and crossed by a few sheep, offers a striking contrast. It reminds that each kilowatt-hour produced through the nuclear route leaves a physical, tangible trace that will cross dozens of generations before it can be considered completely neutralized.