中文摘要：

明长城军堡是与长城唇齿相依共同承担防御任务的一系列屯兵城。作者通过对我国北方近百个军堡实地考察，结合相关史料，初步探讨军堡的选址问题，提出影响军堡选址的因素主要有长城的位置、受作战距离制约、传统风水理论和地形四点，其中地形对军堡选址的影响最直观体现古人“因地形用险制塞”的军事防御思想，根据军堡与自然地理的关系将军堡分为四类，并通过实例分别予以介绍。

英文摘要：

The military fortresses along the Great Wall in Ming dynasty were a series of towns where troops were stationed for frontier defense. Through on-the-spot investigation of hundreds of fortresses and historical researches, the authors bring forward four factors affecting site selection including the location of the Great Wall, the fighting distance, the theory of the traditional Feng-Shui, and the terrain. The location of the Great Wall is a direct factor; the fighting distance dictates that the distribution of the fortresses is thirty or forty Li apart. Terrain has the closest connection with fortress site, as can be seen in Chinese ancestors＇ defense strategy of setting fortress right in narrow pass. The fortresses can be classified into four types according to their relations to the natural surroundings. The first type is located on high mountains; the second is in basins, the third is in the way of the foot of mountain; and the last is in deserts. The characteristics of the first type are as follows. The fortresses are located on mountain tops, and easy to hold but hard to attack, overlooking the surrounding valleys. Most fortresses are small because of the narrow land, but some are large whose ramparts are built along the ridge for effective defense. The characteristics of the second type are that the fortresses are located at the foot of a mountain and beside a river. Usually beacon towers are built on surrounding hilltops for the purpose of observation. The characteristics of the third type are that the fortresses are usually located at a mountain pass, flanked by two precipitous mountains. The fortresses should control the land and water traffic. Therefore it always located near a road, backed with a mountain as a natural barrier against intruders. The characteristics of the fourth type are that the fortresses are in deserts or hilly areas, with neither high mountains nor waters around. Fortresses are an inseparable part of the Great Wall. They contain abundant frontier history and military culture.