The Portuguese built a city wall in Macau, which can be traced back to the third year of Longqing in the Ming Dynasty (1569). It can be seen from the city map of Macau at that time that, except for the inner harbor in the west, city walls were built in the north, east and south of the entire city of Macau, and forts were built at various fortresses, making Macau a castle with tight military defense. The existing ruins of the old city wall are part of what was built at that time.
