The main hall of the Grinding Needle Well, also known as the Ancestral Master Hall, is a brick and wood structure with a hard roof and raised beams. The front is a corridor and the back is covered with eaves. The top of the corridor is a rolled canopy with a black tubular tile roof. It has three bays, a width of 11.14 meters, a depth of 8.3 meters, and a total height of 10 meters. It has a strong folk architectural style. According to records, during the reign of Emperor Kangxi of the Qing Dynasty, there was a caretaker named Li Changgui who successively visited the governor Lin Tianqing, the governor Jin Chaoyong, the prefect Du Yangxing, the prefect Zhong Guoyu and others, saying that Lu Dongbin had enlightened them and they should vigorously build the Pure Yang Palace at the Grinding Needle Well. Therefore, they donated over 100 taels of silver and used more than 700 shi of the mountain's rent grain to build the Pure Yang Palace.