Introduction to Xuanwu Hall: The existing Xuanwu Hall was built in 1997 in front of Gutu Cave to enshrine Zhenwu Patriarch. Gutu Cave is the oldest ancient cave in Laojun Cave, dating back more than 1,700 years. It was first dedicated to Dayu, the hero of flood control. During the Kaiyuan period of the Tang Dynasty, it was renamed Laojun Cave to enshrine Taishang Laojun. In the 11th year of Xianfeng reign of the Qing Dynasty, it was changed to worship Zhenwu Patriarch.