In 1971, the Museum of Fine Arts, Boston presented an exhibition titled Earth, Air, Fire, Water: Elements of Art, organized with Virginia Gunter and accompanied by a catalogue essay by David Antin. It explored artists’ use of elemental materials and environmental processes. In response Robert Smithson developed a proposal for a flatbed trailer that would move through the city. He envisioned collecting rocks and piling them onto the trailer, then driving to a concrete mixing plant where concrete with heavy aggregate would be poured over the load. The plan was for the trailer to be pulled through Boston and parked at various locations.

Art historian Robert Hobbs described the proposal as a mobile monument dedicated to entropy, and art critic Kenneth Baker later observed in Artforum, “if only it hadn’t been squelched by logistical problems.” This drawing from 1970 outlines the method. Another drawing for this project has the annotation: “anything that exacts blind devotion as terrible sacrifice,” drawing on the etymology—something that always fascinated Smithson—of the word juggernaut.