PROMPT: A Black Mass: Warning of Nuclear Waste is an entry for archoutloud.com's NUCLEAR design competition. How do we warn future generations of a toxic waste storage site? This solution provides a large mass that sits on the earth, surrounded by a spiraling field of signposts – all of which are carved from a durable black stone (basalt or harder). The central mass provides a visual cue from a distance and the signposts provide an additional layer of warning, with an off-kilter configuration and symbolic messages. On one side of the black mass is an overhang, and below it, a more descriptive text that alerts the viewer to “danger” in many languages. Together, these objects mark this spot with a cautionary significance. The proposed site is the WIPP facility in New Mexico.