The question of how to mark the places where we store nuclear waste such that people in the distant future won’t do things like build towns or nurseries or farms on top or inside of them is one of my favorite transmedia design challenges. It’s a thought experiment that asks us to imagine a way to communicate with a diverse and unknowable range of cultures and attitudes across a vast gulf of time. Nuclear waste can take upwards of 20,000 years to decay.
Solutions to the problem, such as those proposed by the Human Interference Task Force, a workgroup formed in 1981 by the US government, include the construction of monumental reinforced concrete architectural elements (obelisks, pyramids, and so on, all inscribed with a range of frightening DANGER! symbols), the breeding of super-friendly genetically-engineered cats that change color in the presence of radioactivity, and the establishment of a multi-millennium-scale religious order or “atomic priesthood”.