From the perspective of city construction history or evolution of development history, this thesis clarifies the context of the construction of the brick city in 淡水廳during the Guangxu period of the Qing Dynasty. From the selection and location of city walls and gates, the city layout of the late Qing Dynasty was formed by factors such as the rise and fall of commercial activities in old streets and the evolution of settlement patterns. After the transfer of the dominion to Japan. The government changed the general direction of urban development from closed to open. Through the implementation of 市區改正, the new district, the East Gate area, thrived and the city center was transferred. Emphasize the transformation of the role of East Gate(東城門) in the urban space. (東門城)East Gate which was the entrance and exit of the city in the Qing Dynasty transformed to the city landmark during the Japanese ruling period. The traditional architecture combined with the design of the modern circle plaza constituted an effective use of space in urban planning. The position of both a transportation hub and a city landmark had become a local identity in the memory of all citizens.