Plasticity is often understood as a contemporary interest because of its material associations. This proposal suggests that this is a misconception and that plasticity is a spatial and architectural idea that preceded the material invention. The research investigates effects of plasticity in Baroque and postwar period buildings in Rome by focusing on three aspects of plasticity—superficiality, spatial volume, and illumination. The research takes two trajectories: the first focuses on the poche as a material substance that facilitates interiorized plasticity within a dense urban environment; the second focuses on surface transitions that mediate between distinct spatial geometries. The challenge of this proposal is twofold: first, the need for innovative techniques through which plasticity can be documented and represented; and second, the desire to draw relationships between spatial plasticity and contemporary interest in material plasticity. Both challenges are opportunities to understand how the buildings of Rome inform contemporary architectural ideas.