Why are project leaders of radioactive waste geological disposal centre projects interested in the Giza pyramids, tsunami markers or time capsules? What are they looking for as they venture into the fields of landscape archaeology, archival science and the cognitive processes of intergenerational transmission? Based on a study of the reports produced by the teams of researchers mobilized in the early 1990s by the US Department of Energy and those from the Nuclear Energy Agency's international Preservation of Records, Knowledge and Memory across Generations program, this article aims to better understand the ways in which the actors involved in such projects try to ensure a memory capable of withstanding the multi-millennia durations engaged by certain types of radioactive waste.