In November last year, the translation of a 500-year-old document answered one of the greatest mysteries surrounding the Forbidden City in Beijing, China – how the ancient people managed to transport stones weighing more than 330 tonnes over 70 kilometres. Until now it was believed that they were transported on wheels, however, the ancient document showed that this was not the case at all.

The Forbidden City is the imperial palace that was once home to the emperors of China during the final two imperial dynasties, the Ming Dynasty and the Qing Dynasty. Built in 1406 to 1420, the complex consists of 980 buildings and covers 720,000 m 2. The palace was declared a World Heritage Site in 1987, and is listed by UNESCO as having the largest collection of preserved ancient wooden structures in the world.

The Forbidden City in China is a UNESCO World Heritage listed site. Image source: BigStockPhoto

Vast numbers of huge stones were mined and transported there for its construction, the heaviest of which weigh more than 220 tonnes and would have weighed more than 330 tonnes before they fragmented. It has been determined that the largest blocks came from a quarry 70 kilometres away and since people in China were using the wheel since around 1500 BC, it was believed that this is how the huge stones were transported.

However, Jiang Li, an engineer at the University of Science and Technology Beijing, translated a 500-year-old document and was astonished by what he read. The document described how giant stones were slid for miles on specially constructed sledges , dragged over slippery paths of wet ice by a team of men over 28 days. The workers dug wells every 500 metres to get water to pour on the ice to lubricate it, which made it easier to slide the rocks.

An historical document revealed that huge stone blocks were dragged along ice. Photo credit: Daily Mail

The researchers calculated that the transportation would have required 46 men to move a stone weighing 123 tonnes using this method, and they would have been able to move the stone about 3 inches per second, fast enough for the stone to slide over the wet ice before the liquid water on the ice froze.

The fascinating findings were published in full in the journal Proceedings of the National Academy of Sciences.

The spectacular Forbidden City. Image source: BigStockPhoto

Featured image: The Forbidden City of China. Image source: BigStockPhoto

By April Holloway