How much greater? More than twice as great! A preliminary survey conducted in 2009 estimated that the fortifying structures that comprise the wall measured 8,850km (about 5,500 miles); now, the first attempt to directly measure the wall in its entirety has revealed that it is, in fact, 21,196.18 km long — that's over 13,000 miles!
Writes The Telegraph's Malcolm Moore:
Contrary to popular belief, the Great Wall of China is not a single wall, but instead a series of often overlapping defensive fortifications, some brick and others of packed earth, built over the course of nearly 2,000 years, many of which run parallel to each other.
Beginning in 2007, teams of Chinese surveyors fanned out across 15 Chinese provinces to measure every wall, or trace of a wall, they could find.
"This figure (of 13,173 miles) takes into consideration all of the walls that were ever built, even if they are no longer still standing," said Dong Yaohui, the deputy director of China's Great Wall Association.
Why did it take this long to get an accurate measurement of the wall? For one thing, previous estimates were based almost entirely on historical records; and according to the report documenting the survey, just over 8% of the wall's original structures remain intact (and those that do are in pretty sorry shape). That's made mapping the Wall's physical sections difficult, but it also means that Great Wall experts like Britain's William Lindesay — who told The Telegraph that he was actually disappointed with the updated measurement, saying he expected it to be even bigger — may have more extending discoveries to look forward to.
Given the recent success of satellite imagery in uncovering clues about human history in the Middle East, I can't help but wonder if similar technologies might be used to investigate the true extent of China's fortifying Wall further.