Introduction to the Xuhuang niche: The Xuhuang niche was excavated in the Yuan Dynasty and has a total of 21 statues. The cave faces south and is located at the highest point of the grottoes. The interior of the cave has a circular arc roof and the door is square inside and round outside. On the front wall of the grotto, there is a lotus petal-shaped niche, which contains a statue of the Xu Emperor sitting cross-legged. The head is missing but the long beard is still there. On both sides of the niche, there are 10 standing statues of Tianzun on each side. They all have their feet on auspicious clouds and are arranged in a circle. Some of the heads are missing. Between the caisson and the statue, there is a stone inscription from the Yuan Dynasty, with 49 lines and 190 words in total. The content is selected from "Xuan Gang Lun" by Wu Jun of the Tang Dynasty.