How the Great Wall of China Works

When the first portions of what would eventually become the Great Wall were built, they weren't part of a large master plan to block off China from the north. Instead, beginning anywhere from the seventh century B.C. to the fifth century B.C. (the start date is disputed by archaeologists), many small walls were erected by the six different states that would eventually become China as we know it. The point of the walls was to provide protection from the often warring states as well as a variety of invaders, including the Huns.

In 220 B.C., the Qin Dynasty unified the Qin state with the six other warring states (Han, Wei, Chu, Yan, Zhao and Qi, in that order). The emperor Qin Shihuang then ordered the separate pieces of the Great Wall in the northern states to be connected. He did this to provide maximum security from the troublesome Huns. Thus, the Great Wall began to take shape in its most infantile form.

Construction on the wall, which is made out of several different materials including bricks, stone, grass, rock and earth, continued over subsequent centuries and was completed by Chinese soldiers, criminals and commoners. This imposing structure didn't come without a price, however. It's estimated that thousands upon thousands of Chinese workers died building the Great Wall, and many of them were buried inside the structure itself.

In addition to the Qin Dynasty, other dynasties were involved in the Great Wall's long and complex construction history.

Under the Ming Dynasty, the wall underwent its biggest transformation.

It wasn't until the rise of the Ming Dynasty in 1368 that the Great Wall of China as we know it today was brought to fruition. The Ming Dynasty had to contend with a great number of attacks by minority tribes, so it made substantial additions to the wall.

The complexity and sheer size of the Ming wall outdid all of its predecessors. Not only did the dynasty add length, it also added double and triple walls in some places to reinforce previously built structures and confuse attackers. In fact, in many places the wall is wide enough on top for someone to drive a car on it, averaging an impressive 22 feet (6.7 meters). Although the wall sports an impressive girth, it's not visible from outer space as the old myth claims. If that were true, major highways would also be visible -- many are much larger than the Great Wall.

The Ming Dynasty also increased the military prowess around the wall. Fortresses were placed intermittently along the length of the wall to store military supplies, and beacons were built to provide much-needed light. Another innovation to the wall that the Ming Dynasty introduced was guards. Guard towers were erected at strategic points along the wall from which guards would send out smoke signals and fire cannons to notify each other of possible hostile attacks. The only major downfall to these guard towers is that they were manned by humans, who sometimes fell prey to enemies' bribes and allowed them access to the other side of the wall.

Construction on the Great Wall was an ongoing and successful effort under the Ming Dynasty until the 17th century when China could no longer thwart the efforts of the Manchu, invaders from Manchuria who successfully infiltrated China. This takeover, which brought down the Ming Dynasty and gave rise to the Qing Dynasty, effectively halted the Great Wall's development, which spanned more than a whopping 2,000 years.

The Great Wall isn't just one of the world's most famous landmarks, it's also the only historical monument marked on world maps by cartographers. Understandably, the Great Wall is a magnet for tourism. In fact, more than 10 million people visit it each year [source: BBC News]. While its status as a bona fide tourist attraction results in valuable revenue, tourism and other factors have taken a massive toll on the wall's structural and aesthetic integrity.

First, it's important to note that the Great Wall hasn't exactly been in top-notch condition for some time. Following the Manchu invasion in the 1700s, it was largely abandoned as a military priority. After all, why would the Manchu waste time and energy on something that failed to keep them out? As a result, the wall became overgrown by vegetation and began to deteriorate as a result of earthquakes and exposure to snow, wind and rain. Battles ranging from tiffs with the Huns to high power assaults with Japan in the 1930s and '40s also hastened the wall's decline.

Even local residents' everyday activities have contributed substantially to the Great Wall of China's corrosion. Herding animals and gathering firewood have sped up the deterioration process after years of abuse -- stomping livestock and human tools have chipped away at its edifice. What's more, Mao Zedong holds some responsibility for the damage: He encouraged the Chinese people to use bricks and other parts of the wall to build homes and other structures as recently as the 1950s. Road construction crews have even dared to knock holes in portions of the wall to build highways.

Ironically, the tourism industry is one of the largest contributing factors to the wall's demise. For years, tourists have taken pieces and bricks from the wall as souvenirs. They've etched names and epithets into the wall, and vendors have set up shop with souvenir stores, cable cars, parking lots, fast food restaurants and more within feet of the landmark. Unsightly advertisements, signs and public utilities have shown up in high-traffic areas along the wall, and litter and graffiti have marred it and surrounding areas. Well-meaning tourists and locals have taken it upon themselves to restore portions of the wall in unauthentic and unreliable ways. As a result of all of these factors, a whopping 50 percent of the Great Wall has disappeared entirely, with a remaining 30 percent in ruins and a mere 20 percent classified as being in "reasonable" condition [source: Mooney].

Until recently, the Chinese government was reticent to discourage or limit tourist access to the Great Wall for fear that it would decrease revenue to the area. However, as it has become increasingly clear that the wall is in peril, the government, with input from organizations such as the International Friends of the Great Wall and the Great Wall Society of China, has put laws and regulations in place to stop damage to and properly restore the structure. In fact, the World Monuments Fund added the Great Wall to its list of the World's 100 Most Endangered Sites.

In 2003, the Beijing Administrative Bureau of Cultural Relics enacted regulations to protect the Beijing portion of the wall, which shoulders some five to six million tourists each year [source: People's Daily Online]. The regulation allows the organization the authority to prohibit the construction of any building within 1,640 feet (500 meters) of the wall that can cause either unpleasant aesthetic damage or physical desecration. Seemingly innocent activities that have an adverse effect on the wall have been declared taboo. These activities include pitching a tent, gathering firewood, herding animals and setting up stands to charge admission to less savvy tourists.

Soon after the Beijing regulations were put in place, the Chinese government enacted the first national law aimed at protecting the Great Wall. The government officially prohibited activities like removing bricks or stones from the wall, holding raves or parties on top of it, carving words into the wall or building a home too close to it. Raves and driving and carving on the wall have become such big problems in recent years that in 2006, the government instituted fines of up to $62,500 for institutions and $6,250 for individual violators. In addition to enacting laws designed to protect the Great Wall from further damage, the Chinese government has also allocated funds to allow for continued preservation and restoration of the monument. Advocates encourage individuals to contribute to these efforts in several ways, such as by planting trees, removing litter and making sure to never take anything from the wall or leave anything behind.

Thanks to these efforts, awareness about the Great Wall's status as a historical landmark of intrinsic value and beauty to China and the world has become more established, effectively beginning to turn the tide of centuries of neglect and abuse. Unfortunately, in many of the less metropolitan areas where the wall is located, locals don't understand the cultural significance of the structure. In fact, they continue to routinely use bricks for building purposes. Several men in Inner Mongolia were even accused for removing what they deemed to be a pile of earth from a particularly ancient portion of the wall to use as a landfill. Simply put, many people who are just trying to survive aren't as concerned with a landmark as they are with taking care of their families.

Although it may continue to be an uphill battle for some time, the Great Wall's preservation has been embraced as a matter of the utmost cultural and historical importance, especially because it serves as a gateway into China's storied and colorful history.