the Great Wall of China is the longest manmade structure ever built. It was built to protect one of the Chinese kingdoms. much of what exists of the wall today was built during the Ming Dynasty in the late 1400 although parts of the wall are much older and go back to around 200 BC. the wall is about 35 feet high, or 11 meters, and a stone roadway runs along the top of it. the main pert of the wall stretches for about 2,000 miles, that is, about 3,400 km