The part nobody has opened
The pits of clay soldiers are only the visible fringe of the First Emperor’s burial complex. The central tomb, under a large tree-covered mound a short distance west of the army, has not been excavated. Its present height is often given as about 50 metres, though the original was probably different, because erosion and later changes have altered the mound. Around it lie inner and outer enclosure walls of rammed earth, and a funerary landscape that covers a very large area of ground.
The most important point to state clearly is that no one has seen the main burial chamber in modern times. Everything said about it comes from an ancient text, from remote sensing and from soil tests.
What Sima Qian wrote
The main written description comes from the Shiji, composed about a century after the emperor’s death in 210 BCE. It says that the tomb was begun early in his reign and that large numbers of conscripts worked on it. The chamber is described as containing models of palaces and offices, valuable objects, and automatic crossbows set to shoot intruders. The text also says that rivers and seas were imitated with mercury, that the ceiling represented the heavens and the floor the earth, and that lamps were fuelled with oil expected to burn for a long time. It adds that those who knew about the tomb’s contents were shut inside, and that trees were planted to make the mound look like a hill.
Sima Qian was not an eyewitness. Some of the details may be literary exaggeration, and parts may reflect rumour. The text remains the starting point for every discussion, and the question is how far modern evidence supports it. The idea of the tomb as a cosmos for the dead has parallels elsewhere in thinking about the afterlife, and comparing it with Egyptian afterlife beliefs shows how different cultures furnished tombs with what the dead might need.
The mercury readings
The best-known test took place in the early 1980s, when Chinese scientists analysed soil samples from the mound. They reported unusually high levels of mercury over a substantial part of the area above the burial chamber, which seemed to match Sima Qian’s description. Later surveys in the following decades have been reported to show a similar pattern.
How much weight to give this is debated. High mercury in soil is consistent with large quantities of mercury underground, but it can also come from natural sources or from other causes, and the pattern depends on how samples were taken. The finding is best described as supportive and suggestive rather than conclusive. It does not show rivers of liquid mercury, or how much was used.
What remote sensing suggests
Geophysical surveys using ground-penetrating radar and similar methods have been carried out on the mound and the area around it. Reports describe a large, structured space and walls under the mound, in line with a major burial chamber and perhaps a palace-like layout. The methods have limits: they give indirect readings of buried structures, which must be interpreted. In other fields a similar approach is well established. A LiDAR survey, for instance, can reveal surface features across large areas, but it cannot see inside a sealed chamber, and the Qin tomb is a reminder that there are things survey cannot answer.
A recent comparison comes from Egypt, where non-invasive scanning of the Khufu Great Pyramid has detected hidden voids without opening them. Remote techniques are improving, but they do not replace excavation.
Has it been robbed?
Later accounts say that the rebel leader Xiang Yu looted the tomb after the fall of Qin. Archaeologists have found evidence of early disturbance, including shafts dug into the mound area, which suggests that some robbery or damage took place. Whether the main chamber was reached remains uncertain. The mercury readings and the radar reports have been used to argue that the central structure may be largely intact, but this is an interpretation and not a proven fact.
Why it has not been excavated
Chinese heritage authorities have repeatedly said that excavation of the central tomb is not planned. Several reasons are usually given, and they are practical rather than mysterious.
- Preservation. The experience at the army pits is the central lesson. When the pits were opened, painted surfaces and lacquer faded quickly. Organic materials, silk or wood, could be even more fragile. Excavation without proven methods to stabilise them risks losing the very evidence the project aims to gain.
- Safety. If mercury is present in quantity, it could pose a risk to workers and to the environment. The stories of crossbow traps are generally regarded as unproven, but they are not the main concern.
- Policy and ethics. Chinese policy generally favours protecting sites in place and waiting for better technology. Respect for a tomb of this importance is also part of the discussion, in the way that Japan’s largest Kofun burial mounds, including imperial ones, are mostly left unopened.
- Resources. The many pits already known have not been completely excavated, and they need continuing work.
Nothing prevents the policy from changing in the future, and statements that the tomb will never be opened should be taken with caution. At the moment, though, the position is to keep it closed.
What this means for the Qin story
The unopened tomb is an unfinished chapter. It could one day show how the Qin court imagined death, what was placed with the emperor and how closely the Shiji matches the reality. Until then, the best course is to separate three kinds of statement: what Sima Qian said, what scientific tests suggest and what remains unknown.