A waterway was built in the garden to enable an emperor to enter by boat. Remains of several piers, which were absent in blueprints, were found.
The discovery of these remains may help experts to more accurately determine the time of the garden's construction.
"Archaeological studies and historical records can complement each other," he says.
Some constructional methods used above water are similar to those in Venice.
The similarity does not necessarily mean that China learned from Italy in ancient times, or vice versa, Zhang says.
"However, similar situations may inspire common wisdom among different cultures."
A trail in the rock garden was also found in the recent discovery. Perhaps, Qianlong once stood at its highest point to view a panorama of the complex built at the zenith of Chinese garden construction.
Zhang says many relics indicating olden-day scenes are scattered among the pieces of megalith and will need further study.
Earlier this year, discovery of Ruyuan, a garden in the southeast of Yuanmingyuan, also grabbed public attention.
According to Li Bo, director of the administrative office of Yuanmingyuan Ruins Park, there are 86 visible sites above ground in the park, but many more are buried underground.
"When talking about Yuanmingyuan, many people believe little was left despite its past splendor," Li says. "However, that's not true. Many historical stories are hidden beneath the grass and earth but are neglected.
"We need to better display the sites after excavation. If the Forbidden City in Beijing is a museum for cultural relics, Yuanmingyuan can be a museum for ruins."
