<p>Projection mapping has been widely adopted in the cultural heritage sector as a medium for immersive storytelling and public engagement. However, its content design is often treated as an open-ended creative process, lacking empirical understanding of how the intrinsic properties of heritage architecture may shape visual narratives. This study presents a structured investigation into the influence of architectural attributes, both physical (e.g., scale, surface flatness) and cultural-historical (e.g., designation level, functional legacy) on projection content logic. A dataset of 36 cases was analyzed through content classification, spatial structure mapping, and regression modeling to detect consistent patterns in content selection. The findings reveal that specific architectural conditions systematically affect the representation of historical, mythical, and performative elements in projection design. By revealing the structural and symbolic constraints that shape PJM narratives, this research reframes PJM from a purely creative tool to a culturally grounded medium. It highlights the importance of aligning digital design practices with the spatial and historical logic of heritage sites, offering a more effective and respectful pathway for cultural communication through technology.</p>