This paper introduces a method of post-tensioning granular jammed structures to achieve horizontal spans that can be tuned and morphed, as well as withstand significant vertical loads. The paper begins by discussing recent research into jammed structures. The methods section details the development of the fabrication system that led to post-tensioned, jammed—or “superjammed”—structures. The ability to structurally tune, geometrically morph, and instantly reverse superjammed structures is discussed. The performative possibilities of superjammed structures are demonstrated through the prototyping of large-scale spanning typologies. The results of abrasion testing on a superjammed structure are also briefly presented. The outlook section summarizes the benefits of superjammed structures and outlines further research into their limitations, including load capacity, scalability, and weather resistance.