Introduction to the former site of Purple Mountain Academy: Purple Mountain Academy was founded 700 years ago. It is one of the important birthplaces of mathematics, astronomy and calendar in my country. It has cultivated a number of scientific and cultural leaders in my country such as Guo Shoujing, Liu Bingzhong, Zhang Wenqian and Wang Xun. A genius who has made great achievements in the field and occupies an important position.