Photo taken on June 12, 2018 shows heads of marble dragons at the Subdistrict of Qinghe, Haidian, in Beijing, capital of China. Four heads of marble dragons, unearthed from a construction site, were returned to the Old Summer Palace, also called Yuanmingyuan on Tuesday. They were identified as relics of Yuanmingyuan by experts, thanks to the report from Du Zening, an ordinary citizen. (Xinhua/Luo Xiaoguang)

Workers load heads of marble dragons onto a van at the Subdistrict of Qinghe, Haidian, in Beijing, capital of China, June 12, 2018. Four heads of marble dragons, unearthed from a construction site, were returned to the Old Summer Palace, also called Yuanmingyuan on Tuesday. They were identified as relics of Yuanmingyuan by experts, thanks to the report from Du Zening, an ordinary citizen. (Xinhua/Luo Xiaoguang)

Workers load a marble dragon head onto a van at the Subdistrict of Qinghe, Haidian, in Beijing, capital of China, June 12, 2018. Four heads of marble dragons, unearthed from a construction site, were returned to the Old Summer Palace, also called Yuanmingyuan on Tuesday. They were identified as relics of Yuanmingyuan by experts, thanks to the report from Du Zening, an ordinary citizen. (Xinhua/Luo Xiaoguang)

Workers load heads of marble dragons onto a van at the Subdistrict of Qinghe, Haidian, in Beijing, capital of China, June 12, 2018. Four heads of marble dragons, unearthed from a construction site, were returned to the Old Summer Palace, also called Yuanmingyuan on Tuesday. They were identified as relics of Yuanmingyuan by experts, thanks to the report from Du Zening, an ordinary citizen. (Xinhua/Luo Xiaoguang)