How great is the Great Wall of China? Very!

I bet you thought the name said it all. A recent survey by of this World Heritage site – billed as “technologically advanced” – puts the original length of the wall at 5,500 miles, much further than the previous estimate of 3,700 miles. That’s a difference of almost 50 percent!

This effort took more than two years of surveying with GPS tools, infrared technology and other mapping techniques, and the outcome is the most complete view of the wall ever seen. Since perfectly restored pieces comprise no more than 20 percent of the original wall, this new perspective will help with efforts at conservation.

Erosion and war impeded protection in the past, but the current threat is construction, as China embraces (parts of) a capitalist economy. In some cases, roads exist in places once occupied by the Great Wall of China. Almost a third of the structure has disappeared completely.

More research is on the agenda, with completion expected to come in 2010.