The film takes the "Alchemy Forever" exhibition, the Yangxin Hall research protection project, and the maintenance of ancient buildings as clues, and passes through the Palace Museum's Ancient Construction Department, Restoration Technology Department, Engineering Department, Cultural Conservation Science and Technology Department, Archeology Department and other Palace Museum personnel. From a work perspective, embark on a journey of rediscovery of the Forbidden City. The documentary focuses on the repair and protection of ancient buildings, recording the craftsmen who carefully protect the Forbidden City within the palace walls, showing the wonderful relationship between people from all over the world and this city outside the palace walls, and telling the story of the eternal youth of the Forbidden City.