The Great Wall of China is considered to be the only man-made
project seen from the moon. Although it was once thought to have been built
entirely during the Qin Dynasty (朝代) between 221 and 208 BC, it is now believed
to have been started earlier. The 15-foot-high, 25-foot-wide,
1,500-mile-long structure was undoubtedly built to keep out invading enemies. To
the common people of the empire, who had been forced to build the wall, it was
not worth it, however. The wall, and other public works completed by the Qin
Dynasty, had caused great losses on the wealth and human life of the country. As
a result, an angry population rose up in rebellion (反抗) against the Qin Dynasty,
and in 207 BC the Han Dynasty began. Because of its rich
history and magnificent appearance, the Great Wall attracts tourists,
scientists, and historians (历史学家) to this day and will continue to do so for
generations. What is considered the only man-made project seen from the moon
The ______ of China.