The Great Wall of China was built to link existing fortifications into a united defense system and better keep invading Mongol tribes out of China. It is the largest man-made monument ever to have been built and it is disputed that it is the only one visible from space. Many thousands of people must have given their lives to build this colossal construction. In short - vote for the Great Wall of China, because it is incredible proof of - Perseverance & Persistence!