Yueshou Hall, Qingyiyuan Architecture, is also the main building in the living area of the Summer Palace. The Happy Longevity Hall of Cixi's Bedroom in the Summer Palace of Beijing was originally the mother of Emperor Qianlong who had to celebrate her sixtieth birthday in the fifteenth year of Qianlong (A.D. 1750). In order to celebrate her sixtieth birthday, Qianlong transformed the original Oushan Mountain and West Lake in the fourteenth year of Qianlong.