The secrets of the Great Wall of China - Did you know the Great Wall of China took 20 centuries to be completed? That idle soldiers helped to build it? Or that the wall is known as the world's biggest cemetery?
Check out the gallery and find out more about these and other interesting facts about the Great Wall of China!

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In the beginning - Construction on the Great Wall of China began in 215 BCE.

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Emperor - It was Emperor Qin Shihuang who ordered the construction of the wall with the idea of protecting the the territory from enemy invasions.

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Finishing touches - The last stretches of the wall were erected around 1568.

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Centuries - The wall was not completed for 20 centuries after the first stretch of walls went up.

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Workers - At the beginning of construction, the workers sent to the wall were considered troublesome or unruly people.

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Idle soldiers - Those workers were later substituted by idle soldiers, after the war between the two provinces ended.

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Numbers - It is said that more than two million workers worked on the wall before it was finally completed.

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Cemetery - The wall became known as the 'world's biggest cemetery,' due to the amount of people that died during its construction.

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Dead - An estimated one million workers died during its construction.

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Causes of death - Some records show deaths caused by cold and malnutrition.

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Crossing borders - The wall crosses through nine provinces and 100 counties over its 5,000 km.

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Height - It is 7.8 meters tall and its battlements measures 5.8 meters in width.

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Material - Originally a lot of earth and stone was used in construction, which was later replaced by more efficient bricks.

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Policy - This changed happened due to a political policy in the provinces to modernize construction.

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Sections - The Great Wall was not one continuous construction, it was built in segments and joined up.

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Erosion - In some places the wall has been buried through erosion.

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Wonders of the World - In 2007 the wall was chosen as one of the New Seven Wonders of the World.

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Extension - A new study in 2009 concluded that the Great Wall is in fact 8,850 kilometers in length.

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Man-made - The Great Wall is the longest man-made construction.

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2 year study - This study was carried out by the State Administration of Cultural Heritage of China and took two years to carry out.

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From the moon? - Legend says that the Great Wall of China can be seen from the Moon due to its size, but this is not true.

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Myth - This myth was started by the American magazine 'The Century' in 1893.

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Myth busting - Yang Liwei, the first Chinese astronaut to go to space, confirmed it was not true.

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Marathon - One of the world's toughest marathons takes place on the wall - The Great Wall Marathon.

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Up and down - In this challenge, runners have to run a distance which varies between 8.5 and 42 kilometers due to the ups and downs of the wall.

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Run time - To complete the whole course, runners take about three hours.

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Tourist attraction - It has been a UNESCO World Heritage Site since 1987, and one of Asia's most visited sites by people from all over the world.

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Tourists - More than 10 million tourists visit the wall, especially in areas near Beijing.

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Always something to discover - The Great Wall is one of the world's most famous monuments, but according to writer William Lindesay, it's one that we know least about, as there are always new things being discovered about it.

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