In November 2016, Wu Wei returned to the treasure chest of Gaoxuan Hall of Anda University. After completing my master's degree in Archaeology in the Department of history of Nanjing University in 2013, I entered the Palace Museum by mistake. In fact, this is not my preferred unit. At that time, there were no archaeological departments and posts in the "Palace". Although I specialized in Architectural Archaeology at the master's stage and participated in some investigation and mapping of ancient buildings, I still focused on archaeology and wanted to do research on ancient building materials. After "entering the palace", I was assigned to the project management office, a department I didn't know at all. After admission, I searched on the official website to know that this is the management of ancient building repair projects. I'm a little sad. It seems that I'm going to stay away from archaeology. Unexpectedly, this is a new departure. Shortly after I joined the post, I participated in the repair and protection project of Baoyun building with the division of tasks. Just out of the campus, I am full of curiosity and excitement about everything: what I am curious about is how advanced ideas and technologies are used for the repair and protection of ancient buildings in the Forbidden City; Excited, I seem to be able to show my skills. After all, I also learned some knowledge of ancient architecture. However, when I really participated in it, I was poured with cold water - my previous study focused on the protection concept and shape research, but I couldn't solve the specific problems actually occurred in the repair process, and I basically didn't understand the northern official architecture and technological practices. The most important thing is that you don't understand "jargon". As soon as you chat with the construction personnel, you know you don't know anything. But the ancients were optimistic and curious about the world. Moreover, for the ancients, it was not a matter to go to the construction site, but I changed from "entering the earth" to "heaven". What I do most every day is to climb the scaffold with my camera on my back, observe the rare repair work outside, ask my colleagues, peers, construction parties and craftsmen for advice, take photos of each process and practice of repair with my camera and sort out the records. Not only the projects I participate in, but also I often visit other colleagues' projects to learn. In this way, slowly, I can understand the work of the craftsmen; It took me a long time to see if they were doing well. At this point, I stepped into the door of the ancient building repair circle. During the repair of Baoyun building, I deeply realized that there are many hidden parts of ancient buildings. Many information contained in these parts may be seen again only through repair, and some may subvert previous cognition. In fact, some links in the repair of ancient buildings are the same as the process of archaeological anatomy and excavation, during which a large number of original trace information will be exposed, and many information will disappear and irreversible in the repair process, which needs to be recorded comprehensively and carefully. However, the records of the repair project are inconsistent with the archaeological records. The former focuses on the construction process and does not focus on recording the exposed historical information, which is often passed by. I suddenly felt that I had found a coincidence between Archaeology and the repair of ancient buildings. Since the historical information record of the repair is relatively weak, and the strength of archaeology is the record, why don't I give full play to my archaeological skills and strengthen the record and research in this regard with archaeological ideas and methods! Fortunately, I got a good chance. In 2015, I began to take full charge of the site work of the restoration project of the dagaoxuan Hall of the Forbidden City. With the accumulated experience of Baoyun building project, I want to apply the concept and method of archaeology to the repair and protection of ancient buildings. At this time, I have joined the National Palace Museum Institute of archaeology, a non institutional research institution established at the end of 2013 shortly after I joined the post. I regard the roof of an ancient building as an "archaeological stratum" stacked layer upon layer, break the relationship between all the above information according to the construction level and the superposition generated by the repair in different periods, and make comprehensive and detailed extraction records, so as to obtain the historical information and process practices left by the construction and repair in different periods, so as to preserve the "authenticity" and "integrity" to the greatest extent. Therefore, for the first time, I led the archaeological team of the Institute of Archaeology of the Forbidden City to the roof, arranged exploratory ditches and carried out "archaeological anatomy" on the roof, and made a series of unprecedented important discoveries. At the same time, we numbered, recorded and preserved the important relics found according to the archaeological method, which not only made up for the loss of a large number of cultural relics information during the construction, but also provided a scientific historical information basis for the later repair and protection scheme. Later, it was jokingly called "roof archaeology", which also became a major feature of the archaeology of the Forbidden City. Records and research can not just stay on paper, which is the biggest difference from archaeological work. Archaeology is to return to the interior after backfilling and finishing the excavation; The repair project is to install and restore it after disassembly. The wood base of a building was seriously damaged. Because it had been repaired in different times and had many different forms and practices, the construction unit came to ask us and the design unit what form should prevail for restoration. Wood base is the hidden part of ancient buildings, which is often not reflected in the construction drawings. However, we have made detailed surveying and mapping records in advance, analyzed various existing forms and practices, and determined the original practices. We gave the data and drawings to the construction party. They were very surprised and convinced, and repaired accordingly. In the process of repair, I actually work more as an information recorder. I follow craftsmen and "Archaeology" wherever there is repair. I seem to be back at the archaeological site. The "Archaeology" on the roof let me find my unswerving pursuit direction - making archaeology into the characteristics of the Forbidden City and even Chinese characteristics in the Forbidden City, which also made me deeply feel the extension and vitality of archaeology. The information found from the unloaded tiles, wood, bricks and other components seems to be telling me a silent history book, and like films showing me the people, culture and society at that time. (outlook new era)