中文摘要：

以明代宣府镇城为例,研究明长城＂九边＂防御体系中最高级别的防御设施镇城的建置、功能及演变。依据历史资料推测出宣府镇城的空间功能构成图,还原其历史空间。从其最初建置、战略选址、功能构成、形态演变和精神层面等角度进行解析：宣府镇城的建制及演变受到自然条件、边防形势、经济生活以及礼法与社会观念等因素的共同影响。从防御效果看,＂固若金汤＂依靠的不仅仅是防御体系的设置和防御设施的构筑,还需要考虑军事实力、防御战略、人心向背等诸多因素。

英文摘要：

Picks Xuanfu Town,one of the military towns on the highest level of defensive unit in the＂Nine frontiers＂,as the research object,to analyze the establishment and evolvement of Xuanfu.Mapping the plan of the Town according to historical materials,it’s to reappear the ancient space.Analyze the Xuanfu’effects and defensive functions from the perspectives of originated thinking,the strategic intent of the site,the functional setting in the town planning,the specific form of urban space,and spiritual sustenance in the religious buildings,etc：establishment of Xuanfu was effected by natural conditions,military defenses,financial needs and etiquette and social minds.From the defensive results, ＂strong＂depends on not only the defense system settings and defense facilities,but also by military strength,defense strategy,people support and many other factors.