Introduction to the Tianwang Hall: The Tianwang Hall, the mountain gate of Kaiyuan Temple, was built in the third year of Chuigong reign of Wu Zetian of the Tang Dynasty (AD 687). It has been destroyed and rebuilt after several fires. The existing building was built in the 14th year of the Republic of China (AD 1925). On both sides of the hall are the Mysterious Vajra and the Brahma King.