The Great Wall (Wanli Changcheng) is one of mankind's greatest achievements and dates back more than two millennia; when a series of shorter walls were systematically linked during the Qin dynasty (221-206 BCE) to protect China's northern borders.

The Wall; originally built to keep out barbarian invaders from the north; stretches more than 5;900km (3;700 miles) from the Bohai Gulf in the Yellow Sea to Jiayuguan in the mountains of Gansu province. While the bulk of the wall is now in ruins; some sections have been repaired in recent years.

The Ming rulers; who in 1368 put an end to the alien Mongol Yuan dynasty; forcing them back to their ancestral homelands outside the wall; decided to rebuild the Wall into a formidable barrier; the 'Ten Thousand Li Great Wall'. This enormous project took over 100 years; but in the end failed to prevent the invasion of China by the Manchus in the mid-17th century. As a result; much of the wall in northeast China today dates back to the Ming period.