Nanjing library can't enter directly. Nanjing library needs to make an appointment in advance or enter with a reader's card and ID card. Visitors can make an appointment through WeChat WeChat official account or on-site code scanning in Nanjing Library to obtain the reservation code. After presenting the reservation code, scanning code and travel itinerary code, you can enter the lobby without an ID card. To enter the library area, you need to apply for a library card or a reading card. Ordinary readers need to swipe their reader's cards or reading cards when entering the corresponding venues, and opaque bags need to be stored or placed directly outside the venues. Nanjing Library is located in Xuanwu District, Nanjing City, China. It is the third largest library in China, the fourth largest library in Asia, a national first-class library, a provincial public library in Jiangsu Province, a document information resource guarantee and service center in Jiangsu Province, the first batch of national key protection units of ancient books, and the first batch of national ancient books restoration centers.