Recovered artifacts from the Southern Song mausoleums include a decorative ceramic beast figure. [Photo provided to China Daily]

The complex's origins date to 1131, when Empress Meng, widow of the Northern Song (960-1127) Emperor Zhezong, died in exile during the dynasty's frantic southward flight from the Jurchen people in the north.

She was provisionally interred at the foot of a mountain in the city's Fusheng town. This unintended event marked the founding of what would become the most concentrated royal burial ground in Jiangnan, the region along the southern bank of the lower reaches of the Yangtze River.

Seven years later, the Song court established its temporary capital in Lin'an (modern Hangzhou). Over the next 144 years, six subsequent Southern Song emperors and their empresses were buried here.

Notably, the first emperor laid to rest was Emperor Huizong, whose capture by the Jurchens led to the Northern Song's collapse. Huizong's posthumous return and burial here were a paramount concern for his son.

The site's original name, Mount Cuangong, meaning temporary palace, reflected the dynasty's enduring hope. These tombs were seen as provisional, a solemn promise that one day they would reclaim the north and rebury their ancestors in their original imperial tombs in today's central Henan province.

This is why the complex is traditionally called the "six" mausoleums, counting only the Southern Song emperors and consciously omitting Huizong, who was a Northern Song ruler, experts explain.

According to the royal ritual, an emperor's tomb was required to sit southeast and face northwest with its south side higher than the north, creating a descending slope.

Ultimately, a location northwest of Empress Meng's temporary burial site was chosen.

The discovery of the seventh chamber was no lucky accident, Li notes.

It is the fruit of a systematic, 13-year-long archaeological project by the Zhejiang cultural relics and archaeology institute.

"Ours is a long-term, continuous, and meticulously planned operation," Li states.

Since 2012, his team has surveyed the entire 2.3-square-kilometer area. In 2023, they shifted focus to the northern section.

Using traditional manual drilling, they identified several promising spots, ultimately choosing the highest point for excavation as it best matched the classical royal tomb layout of "sitting against the hills and facing the water".

Li points out that the shicangzi is not merely a tomb chamber but the core of the entire burial.

It was a sophisticated, multilayered structure, beginning with a deep pit, he explains.

Then, massive stone slabs were used to construct a nested, rectangular stone casing, with gaps sealed by a type of tamped earth that hardens like concrete.

"An imperial coffin was placed within an inner, smaller stone chamber. The entire structure was then covered, and the turtle-head hall was constructed above it, serving as a protective shelter," he says.

The difference between an emperor's and an empress's tomb was most evident in the size of both the stone chamber and the aboveground architecture, he adds.

The most telling aspect of Mausoleum No 7 emerges when compared to the earlier Mausoleum No 1 from the southern section of the burial cluster.