This writing is a result of initial research to study the morphology of Banten Port City located in the west part of Java, Indonesia, during the early stage of the development in the 16th century. The aim is to build the basic knowledge for further research on seeing the historic cosmopolis transformation and urban culture in Indonesian antique cities such as Banten. This research is an architectural and urban history study that relied on 16th-century historical data included local and colonial histories available in various maps, drawings, records, and journals. In conclusion, The Islamic Sultanate of Banten developed this port city and its urban culture as a continuation from previous customs. Built as a fortress city, the division of living area between inside or outside the fortress wall is determined by the citizenship status. Characterized as a city-state that applied urbanism focal concept, Banten followed a centralized pattern where the center became a sacred place. While the dynamic cosmopolitan atmosphere can be felt outside the fortress where the foreigners from different ethnicity and area lived. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.