Yiyun means the collection of books. The hall was originally built in the 15th year of Emperor Qianlong’s reign (1750) with two side wings, each with five bays. The east wing was named the “Method Keeping Room” and the west one was named the “Nearing the West Room”. Burned down by the Anglo-French Allied Forces in the 10th year of Emperor Xianfeng’s reign (1860), it was rebuilt in the 12th year of Emperor Guangxu’s reign (1886) to serve as a residence for the Empress.

These were the living quarters for Empress Long Yu when she, as Emperor Guangxu’s wife, stayed in the Summer Palace. A niece of the Empress Dowager Cixi, she had the title of Empress bestowed on her in the first month of the 15th year of Emperor Guangxu’s reign (1889). When Emperor Guangxu and the Empress Dowager Cixi died of ill health and Puyi became Emperor in 1908, she was elevated to the position of Empress Dowager under the imperial title of Long Yu. In this capacity, she issued an order to give up the throne in 1911 after the Wuchang Uprising.