Over 2,000 square meters were excavated this year. And archaeologists will expand the research site in 2019, says Zhang Zhonghua, leader of the archaeological team, who revealed the discovery to the public in Beijing last week.

Many stone relics, including towers, palaces, roads, sewage systems and bridges, were also unearthed.

"I didn't expect so many findings because villagers from the surrounding area built new constructions after Yuanmingyuan was destroyed," Zhang says.

Local people built and abandoned three villages in the area after 1860. But most of Zibi Shanfang's foundations survived.

Zhang says the more than 2-meter-high foundation of the main hall in the garden was unearthed, and 2 meters are still underground.

"I've never seen so thick a foundation among the remains in Yuanmingyuan, which may show the great importance of this structure," he explains.

"The foundation is even more solid than reinforced concrete today. It reflects the high level of craftsmanship at that time."