Introduction to Huandu Building: The second floor of Chen's fifth floor is called "Huandu Building". It is located at the back of Cishu Building and adjacent to Xi Building. Taking its meaning from Tao Yuanming's "Already plowing and planting, but also reading my books from time to time", it is a private library built by Chen Baochen. Chen Baochen loved reading and collected a large number of folk rare and rare books. However, because they were not "gifted by the emperor", he was not qualified to hide them in the "Ci Shu Lou", so he condescended to be "Huan Du Lou". The number was even more impressive than that in the "Ci Shu Lou" , its quality sometimes exceeds the rare books in the "imperial collection", and it is the largest private library in Fuzhou.