Located at the mouth of the Tiber River, about twenty kilometers from Rome, the city of Ostia initially played a secondary role in supplying the capital. During the High Empire, when Rome's population approached one million, the emperors Claudius and Trajan commissioned the construction of a vast port complex in Ostia, making it Rome's main port. The first part of this study focuses on the architectural features of Ostia's shops and their evolution, which appears to have been largely driven by the changing role of the city as a port in the 2nd century and the resulting population growth. The second part examines the place of shopkeepers and their activities within Ostia's economy, where port, maritime, and construction trades predominated. From the mid-3rd century AD onward, Ostia's economy seems to have undergone a restructuring centered on more local and regional issues. The final section examines how shops have contributed to structuring the urban landscape. From the main shopping street to the backyards of buildings, including questions about the existence of specialized districts and the strategies used by shopkeepers to attract customers, it becomes clear that shops have played a major role in the emergence of a new urban image.