Although the forces or impetuses that influence an urban structure are diverse, as has been fully studied by scholars from diverse research fields, some have played key roles. We endeavor to explore the key forces and mechanisms forming and transforming the urban spatial structure through Hangzhou, a multi-identity city. Upon studying classical ancient texts, historical maps, critical and recent literature, and POI data, we argue that the first and foremost driver of Hangzhou is commercial culture, rather than any other factors. Under a diachronic view and with graphic analysis, we distinguished Hangzhou’s three major transformations during the last 900 years. Each transformation was, respectively, driven by the complicated commercial culture, which was mixed up with other elementary cultures, such as civil, leisure, landscape, and industrial. Furthermore, urban heritages were formed, inherited, revitalized, and reutilized during the transformation processes, which, in turn, enriched the commercial culture and vividly reshaped Hangzhou’s urban structure.