Cerium has one of the most intriguing phase diagrams among the elements. Even after decades of study, experiments performed under apparently similar conditions have produced different high-pressure structures. This raises a deceptively simple question: does pressure determine the structure, or does the route taken to reach that pressure matter just as much? In this talk, I will show how we used time-of-flight neutron diffraction to follow ultra-high-purity cerium along different pressure-temperature pathways between 85 and 295 K and up to 8 GPa. Slow compression at room temperature predominantly produces a strongly textured orthorhombic phase, whereas compression at 100–120 K produces a monoclinic phase. The monoclinic structure can survive metastably almost to room temperature, but modest heating or pressure cycling pushes the material toward the orthorhombic form. Even more surprisingly, a small amount of the original low-pressure phase remains trapped throughout the experiment, persisting far beyond where it would be expected from the equilibrium phase diagram. The ability of neutrons to penetrate the pressure cell and probe a large, representative sample volume was central to detecting this persistent phase coexistence and following the development of transformation texture. The results suggest that cerium retains a structural memory of how it was compressed, with inherited microstructure helping to determine which phase forms next. I will discuss what this means for the cerium phase diagram and, more generally, for how we identify “the” structure of a material under pressure.