He Yu, a history professor at Renmin University of China, said looters brought further misery to the Yuanmingyuan ruins in the early 20th century. In addition, the layout of Yuanmingyuan was also altered due to later urban development.

"All of the texts and all of our imagination could not compete with the real Yuanmingyuan represented by the photos," He said.

"The site suffered from major upheavals even after 1860. These photos not only provide abundant historical information, but also remind us of how it gradually fell into ruin."

Much effort has been taken to protect Yuanmingyuan since 1976, when the administration of the ruins was established. A current focus of the administration's work is to restore the original landscape, vegetation and the layout of the waters in Yuanmingyuan, said Li, deputy director of the administration.

These photos are of immense value to people today who are striving to restore some of the former glory to Yuanmingyuan.

"These will greatly help our effort to look for lost relics and partially restore the appearance of Yuanmingyuan," Li said.

This work is already taking place, with December's launch of the project to restore unearthed glazed tiles in the Xiyang Lou area by using some photos taken in 1873 as reference.

Li added that more old photos shedding light on the past glory of Yuanmingyuan will be publicly exhibited in the future.