The exact length of the Great Wall of China has not been ascertained yet. The main wall is estimated to be 3,460 kilometers long whereas the aggregate length of the branches diverging from the main wall is estimated to be another 2,860 kilometers. Maintenance and repairs were neglected since the 16th century as the threat of invention receded. As a result it has crumbled at a number of places. For example, about 51.5 kilometers stretch has tumbled down since 1966. Even the government had demolished a few kilometers long stretch of the wall in order to use the stone slabs for the construction of a dam.
Nowadays the Great Wall has become a great tourist attraction, so the market savvy communist government of China would like to capitalize it. Therefore it would like to have the disputable issue of the exact length of the Great Wall settled definitively. In 1985 China had claimed the aggregate length of the Great Wall to be 9,980 kilometers but its authenticity was not substantiated.
Great Wall of China (Wikipedia)