The Great Wall Of China

Even if this claim isn't totally accurate, the Great Wall of China is believed to be the only object visible from space. Whatever the case, it's a long, amazing structure—about 5,500 kilometers. Originally built to keep the nomadic invaders from the north out, it is actually made up of several walls, some of which are parallel to one another. The first wall was constructed somewhere in the third century BC, although it was continually expanded by succeeding kings. The Ming era is when the Great Wall of China's best-preserved section was built (1368-1644).

The wall is currently in poor condition as a result of wear and tear brought on by constant exposure to wind and rain, as well as plants growing inside the walls that have hastened the destruction. About 30% of the wall has been lost over time. The Great Wall of China, one of the oldest historical landmarks in the world, may not last much longer because of the increasingly harsh and unpredictable environment.

• Country: China