In 1624, Dutch East India Company (VOC) set up a trading post in Taiowan in southern Taiwan (now Anping, Tainan) and there built Fort Zeelandia on a hill. After years of expansion, this fort was developed into a large-scale fortress which comprises four parts – the upper main fort, the lower main fort, the earth foundation and the outer fort. Inside Fort Zeelandia, there were a variety of buildings including a governor’s house, houses of company staffs, barracks of soldiers, houses of slaves, warehouses, arsenals, prisons, a church, etc. In the Dutch rule period of Taiwan (1624-1662), Fort Zeelandia did not only play a role in military defense but also had the functions of administrative governance and cargo storage. Undoubtedly, Fort Zeelandia was the largiest military building complex of the Dutch VOC in the 17th-century East Asia and the most prominent and significant multi-purpose building in Dutch Formosa. On account of the significance as mentioned above, this paper consists of two main parts, and each part aims to explore one important theme related to the architecture of Fort Zeelandia. The first part discusses the construction process of Fort Zeelandia. By means of the analysis and comparison of a variety of historical texts and images, this paper in the first place divides the construction process of this fort into five main stages and then reviews the historical background of each stage, such as the management and development of the Dutch VOC in Formosa, the respective attitudes of Governor-Generals in Batavia and Governors in Formosa toward the defense of Taiowan, and the various enemies and natural disasters that threatened Formosa or Taiowan. Under the historical background of each stage, an in-depth discussion of the construction works, the personnel involved in the construction works, the sources of building materials, and the constructional and formal characteristics of Fort Zeelandia will be conducted. On basis of the above discussion, this paper presents a chart as the overview of the construction process of Fort Zeelandia, which shows the important projects in the five main stages, the years when the significant projects were carried out, and the relationship between the governors’ terms and the construction process of this fort. The second part analyzes the relationship between the architecture of Fort Zeelandia and the early modern ideas of European fortification design. This paper first reviews how Italian Renaissance influenced the progress of the European fortification design in the early modern period and then introduces the fortification design of the so-called ‘Old-Netherlands System’ developed during the Eighty Years’s War (1568-1648). Moreover, according to several examples of fortification design in the Netherlands and the Asian posts of the Dutch VOC, the obvious principles of the Old-Netherlands System will be clarified. Finally, by means of the comparison between these principles and the formal craracteristics of Fort Zeelandia shown in the historical images, this paper will further analyze the relationship between the early modern ideas of European/Dutch fortification design and the architecture of Fort Zeelandia. On the basis of the above analysis, this paper confirms that the architecture of Fort Zeelandia to a great degree reflects the early modern ideas of European and Dutch forfification design. However, this paper also points out some formal characteristics of Fort Zeelandia which can hardly be explained by the modern ideas of European or Dutch forfification design. These formal characteristics are probably the results of other reasons or motives which are worth further discussion in the follow-up research.