Around 30%, or 1,962 kilometers of the Great Wall of China has disappeared over time due to adverse natural conditions and reckless human activities – including stealing the bricks to build houses. The Great Wall is not a single unbroken structure but stretches for thousands of kilometers in sections, from Shanhaiguan on the east coast to Jiayuguan in the windswept sands on the edge of the Gobi desert. In places it is so dilapidated that estimates of its total length vary from 9,000 to 21,000 kilometers (5,600 to 13,000 miles), depending on whether missing sections are included. Despite its length, it is not – as is sometimes claimed – visible from space. Construction of the Great Wall first begun in the third century BC, but nearly 6,300 kilometers were built in the Ming Dynasty of 1368-1644, including the much-visited sectors north of the capital Beijing.
Read the full story on the Great Wall of China.