At the end of the time, on the ridge in the northern suburb of Beijing, the construction of two repair sections of the Jiankou Great Wall was in full swing. The "west wall" located in the west of the Jiankou Great Wall is the site of the fourth phase of the Jiankou great wall renovation project. There are eight enemy platforms on the 1678 meter long wall. According to the plan, the fourth phase of the renovation project will be completed by the end of October. At present, about 70% of the project has been completed. In the repair of the Great Wall, we still adhere to the principle of "minimum intervention and repair as old", try to use old bricks and follow the ancient method, and keep the "old" of the Great Wall on the premise of ensuring the safety of the Great Wall. This has been the mature experience of Beijing in the repair of the Great Wall in recent years. A "research repair" is being carried out on the 486 meter long wall (141-145 enemy platform) southeast of the "west wall". Unlike the general repair works, the research repair not only needs to eliminate risks and strengthen, but also needs to study the evolution process, disease causes and storage environment of the great wall through the cooperation of archaeology, architecture, materials, construction technology, plants and other disciplines. At the scene, Shang Heng, an associate researcher of the Beijing Institute of archaeology, pointed to a collapsed wall at No. 145 enemy platform and said: "the remnant appearance is part of the ancient ruins culture of the Great Wall. We chose to keep this collapsed state rather than restore it, so that more people can understand the root cause of the wall disease and the collapse sequence." Since 2021, Beijing has shifted the focus of the protection of the Great Wall from general protection projects to research-based repair projects, which is a new exploration of the protection and repair of the Great Wall. Through early archaeology, the research repair of Jiankou Great Wall has completed the excavation of enemy platforms 145, 144 and 143. The cultural relics protection personnel have clarified the architectural form and engineering practice of the enemy's platform. They have discovered for the first time the relics of living facilities such as the fire Kang and stove site of the Ming Dynasty inside the enemy's platform. They have also unearthed cultural relics such as stone tablets, tiles and weapons of the Ming Dynasty, which are helpful to understand the life of the ancient border guards and provide design basis for the subsequent repair plan. Jiankou great wall repair project is a key project of the Great Wall National Cultural Park (Beijing section). At present, the Jiankou Great Wall with a total length of about 10 kilometers has been completed and the section under repair has reached 5 kilometers. With the approval of the State Administration of cultural relics, the first national practice base for the protection and restoration of the Great Wall was set up at the foot of the Jiankou Great Wall in September 2020, which has played a demonstration and promotion role in the protection of the Great Wall throughout the country. (news agency)