The Great Wall (1) _____ for 5,000 kilometers across China from the East coast to the Gobi Desert. This biggest of all building projects was begun 2,000 years ago during Qin Dynasty. Separately built walls were all joined up to form one huge line, supposedly to (2) _____ any invading nomads. The project used thousands of workers, many of whom were prisoners. (3) _____ 180 million cubic meters of earth were used to form the wall’s core.

The wall was not particularly successful as a deterrent to invaders. However, it was very useful as a kind of ancient, elevated motorway. Men and equipment could be easily moved along the wall, through the previously inhospitable, mountainous land.

Also, a very useful communication system was developed between the different sections of the wall. Smoke signals were used (4) _____ messages quickly anywhere along the wall’s length.
Now, the Great Wall is China’s most popular tourist attraction. It has suffered some decay and destruction over the centuries. Parts have been worn away by the wind and weather. Other sections have been destroyed by local peasants who carried off the materials to make their own homes. However, the wall is still a(n) (5)_______ sight, and a lasting monument to the ancient Chinese civilization that created it.