世界上最长的地下军事防御工程

赞皇地下长城位于河北省赞皇县的东部，背靠太行山脉，东临平原，是一个历史悠久且神秘的地下军事工程。地理坐标为东经114°35′～114°35′，北纬37°46′～37°46′。 赞皇地下长城的地下通道网络纵横交错，总长度达数百公里，是中国古代军事防御体系的重要组成部分。这些地下通道主要分布在赞皇县的数个乡镇之间，形成了一个庞大的地下防御网络。地下长城的主要部分位于地下数米至数十米深，通道高度一般只能容纳单人通过。 地下长城的建造可以追溯到明清时期，是为了防御外来侵略而建造的。这些地下通道不仅包括了长达数十公里的连续走廊，还有藏兵洞、存粮洞和休息室等设施。地下长城的设计巧妙，通道错综复杂，设有多个出入口和秘密通道，充分体现了中国古代军事防御建筑的智慧。 

The Zanhuang Underground Great Wall is located in the eastern part of Zanhuang County, Hebei Province, backed by the Taihang Mountains and facing the plains. It is a historic and mysterious underground military engineering project. The geographical coordinates are 114°35′E to 114°35′E, and 37°46′N to 37°46′N.

The network of underground passages of the Zanhuang Underground Great Wall crisscrosses extensively, stretching for hundreds of kilometers, and is an important part of China's ancient military defense system. These underground passages are mainly distributed between several towns and villages of Zanhuang County, forming a vast underground defense network. The main parts of the underground Great Wall are located several meters to tens of meters underground, with passageway heights generally only allowing for single person access.

The construction of the underground Great Wall dates back to the Ming and Qing dynasties, built for the purpose of defending against foreign invasions. These underground passages include continuous corridors extending for tens of kilometers, as well as facilities such as hidden soldier chambers, grain storage rooms, and rest areas. The design of the underground Great Wall is ingenious, with complex and interwoven passages, multiple entrances and exits, and secret passages, fully reflecting the wisdom of ancient Chinese military defense architecture.