Wall of China has 7,200 km

The Wall of China, one of the biggest workmanships of engineering of all the times, was constructed as prohibited against the invasions of the mongóis and manchus, in year 250 before Christ. Recently one uncovered that the wall is still more extensive of what it was imagined, having seven a thousand and two hundred kilometers of length. The number of laborers is evaluated in ten million who had worked in its construction during 20 years.