_{Amanda Hart, age 10, of Mesa, Ariz., for her question:}

_{HOW LONG IS THE GREAT WALL OF CHINA?}

_{Longest fortified line ever built is the Great Wall of China. It extends more than 1,500 miles through northern China from Shan hai kuan on the east coast to Kansu province in north central China.}

_{The Chinese people often call it the Wall of Ten Thousand Li. Li is a Chinese measurement that equals one third of a mile.}

_{The wall is about 25 feet high. Every 200 to 300 yards there is a tower that is about 35 or 40 feet high. The wall tapers from a width of about 25 feet at the base to about 15 feet at the top.}

_{The sides of the wall are made of earth, brick and stone. The top is paved with bricks that are set in lime, forming a roadway for horsemen. It was all built by hand and took hundreds of years to complete.}

_{Archaeological investigators say the wall was built before the Chin period in 200 B.C. and expanded during the Sui dynasty in 600 A.D. and during the Ming dynasty after 1370.}