One masterwork in Emperor Qianlong's collection. [Photo provided to China Daily]

Elusive painting

In hindsight, too, the emperor had other reasons for regret, Wang said.

"Qianlong always craved for a long scroll titled A Trip Up the River at Qingming Festival," he says, referring to the Song Dynasty painting depicting a bustling riverside scene during one of China's festivals. When it was put on view at the Shiqu baoji show this year, 170,000 people viewed the painting, some waiting in line for six hours for little more than a scant glimpse.

"Throughout his life, Qianlong searched high and low for that legendary painting, but to no avail," Wang said.

"Months after he died, his son and successor, Emperor Jiaqing, prosecuted a favorite official of his father held to be corrupt. His assets were confiscated, and there it was, the famous painting that was still at the top of Qianlong's wish list the day he died."