An important military fortification in ancient times, the Great Wall runs thousands of kilometers on the vast territory of China. From the Yalu River in Liaoning Province, it snakes westward across mountains, deserts and snow-covered plateaus. In 1987, the Great Wall was put on the World Cultural Heritage list by UNESCO. But hundreds of years earlier, it had been reputed as one of the Seven wonders of the world. Only a great nation could have made such a great monument.
