Zhangbi tunnel wall

There is a small pit on the wall of the tunnel at regular intervals, which is the place to put the oil lamp. There is a soil trough for feeding livestock on the high floor; There is an earth hole that can accommodate two or three people at intervals below the middle cave wall, which is an authentic sentry; There is a deep hole 2-3 meters wide and 4-5 meters long on the ground floor, which is a cave for storing food. Such a huge and complicated underground project is by no means beyond the power of ordinary people, but a military need and a confidential strategic facility. According to the textual research on the statues of Liu Wuzhou and Wei Chijingde in the castle, it is considered that it was built in the second year of Tang Wude (6 19), which was done by Weichi Gong when he helped Liu Wuzhou to stop the war, and it is the relic of "building castles by the Ming Dynasty and digging tunnels by the dark".