The main hall of Hall of Mental Cultivation in Palace Museum in Beijing. Photo: Xinhua

After nearly a decade of research-based conservation and systematic restoration, the Hall of Mental Cultivation, or Yangxin dian, at the Palace Museum reopened to the public in Beijing on Friday. 

Since 2015, the project has effectively addressed structural issues in the building, restored and sustained the health of the hall area, and improved the conservation environment for the interior artifacts.

The main hall of Hall of Mental Cultivation in Palace Museum in Beijing. Photo: Xinhua 

According to the Palace Museum, numerous long-hidden historical details and the ingenuity of ancient craftsmanship came to light during the restoration. 

During the "dissection" of a drainage column in the auxiliary structure of the main hall, workers discovered that the internal metal pipe was made of a tin-lead alloy, a material offering properties such as water resistance and atmospheric corrosion resistance, making it well-suited for drainage purposes.

The transparent skylight on the north wall of the Eastern Warm Chamber, used for admitting light, was carefully examined and analyzed. It was confirmed to be a “shell-made window tile” crafted from thousands of polished oyster shells sourced from the ocean. This material is both translucent and flexible, shimmering and shining brilliantly in sunlight. 

Furthermore, within a brick-carved ventilation opening, two sheets of opera performance programs from the Qing Dynasty (1644-1911) for Spring Festival celebrations were discovered, providing precious physical documentation for the study of imperial entertainment culture.

The Hall of Mental Cultivation was built in 1537 during Ming Dynasty (1368-1644) and rebuilt during the reign of the Qing Dynasty’s Yongzheng Emperor (1722-1735). The Yongzheng Emperor had the entire area repurposed from the former imperial workshop to the imperial office where he lived and handled state affairs.

The infusion of modern technology empowered the restoration work with greater precision. The restoration team utilized 3D scanning technology to create digital archives for all artifacts, clearly documenting traces of structural deterioration and weathering. To address the challenge of lighting in ancient building halls, they researched and implemented fiber optic lighting adjustment systems, optimizing the visitor experience while ensuring the safety of the artifacts. 

The conservation and restoration of movable cultural relics in the Hall of Mental Cultivation were carried out in strict accordance with the principles of cultural heritage conservation. Leveraging technological advancements, digital technologies were introduced as auxiliary tools in the restoration processes, achieving excellent results. 

Over the past decade, nearly 500 artifacts, including various objects, calligraphy, and paintings, as well as 120 sets of interior decorative components, have been preserved and restored. Specific restoration work included 4,326 repaired sections, 248 reshaped components, 89 appliquéd paintings, 617 partition panels, and 88 inscribed boards and couplets.

The display of the Hall of Mental Cultivation preserves the authentic arrangements from the reigns of the Yongzheng, Qianlong, Tongzhi, and Guangxu emperors, featuring a total of 1,020 displayed artifacts, said Wen Ming, the Palace Museum's Deputy Director of the Court History Department, Xinhua reported on Friday. 

The main chamber of the hall is arranged according to its appearance during the informal imperial audiences held since the Yongzheng reign. His son the Qianlong Emperor kept three cherished calligraphic masterpieces in the westernmost chamber of the Hall and named the chamber the Hall of Three Rarities, or Sanxi Tang.

The Eastern Warm Chamber, which has undergone the most significant changes in interior layout within the hall, follows the scene where the practice of "ruling behind a curtain" by the Empress Dowager Cixi (1835-1908) took place in the late Qing Dynasty.

All 184 paper- and silk-based cultural relics, including calligraphy works, paintings, inscribed boards, and couplets, along with 255 textile artifacts, have been uniformly replaced with high-quality replicas for the display. 

This measure allows the originals, which are highly sensitive to light, to be preserved more effectively in the controlled environment of the storerooms, while maintaining the authentic visual effect of the Hall of Mental Cultivation’s historical restoration display.