China Letter Clifford CoonanStanding on the Great Wall looking out to where hostile armies from the north once threatened the Middle Kingdom, it's easy to understand how the structure gave China's long-dead emperors a sense of security.
Its stout ramparts look down over steep mountainsides and hilly, difficult terrain, offering one of the world's most spectacular views.
Over 20 centuries old, the Great Wall once stretched almost 6,500km through China and was long believed to be the only man-made structure visible from space. But these days, China's national symbol is in a sorry state, with only 2,500km of the vast defensive structure left standing.
The Great Wall was never actually used to withstand an attack - it was weakness and corruption within the imperial government, rather than the ramparts themselves, which led to invaders being able to pass it to get to Beijing. Legend has it that Genghis Khan bribed his way past the guards to get into China. Rampant development, 10 million visitors a year and party animals are doing more damage to China's most famous landmark than Mongol hordes ever did.
Entire sections of the wall have been knocked down to make way for motorways and housing developments. The Great Wall Society, a non-governmental organisation charged with conserving the structure, said villagers living in its shadow are plundering the wall for stones to build pigsties and henhouses.
Since December 1st, the Beijing government has introduced a raft of new measures to protect the longest wall in the world, which has been on Unesco's list of World Cultural Heritage sites since 1987.
The new regulations oblige "all citizens, legal entities and organisations" to protect the wall and report illegal activity to local government offices.
The rules forbid taking away earth, bricks and stones from the wall; planting crops on the wall; daubing and writing on the stones; installing facilities unrelated with Great Wall protection; organising activities in sections of the wall declared off-limits; and other activities forbidden by laws to protect China's cultural relics.
Anyone violating the regulation faces fines of up to 50,000 yuan (€5,000), while institutions can be fined as much as 10 times that.
"Inappropriate tourist activity has caused damage to the Great Wall and its historical features," an official from China's cabinet, the State Council, said.
The wall was first built during the Qin Dynasty (221-206 BC) in one of the biggest feats of engineering the world had ever seen, involving hundreds of thousands of workers, including soldiers and prisoners. The workers were often attacked by roaming gangs of brigand while working. Legend has it that when the workers died, their bodies were put into the foundation and it became known as the "longest graveyard in the world", although it's unlikely this actually happened. Bodies would make the structure unsound.
It was rebuilt during the Ming Dynasty (1368-1644) but the demise of the Ming meant the end of the wall's importance - the new Manchu rulers actually came from north of the wall, one of the tribes of warlike bannermen the structure was originally conceived to keep out. In 1644, the Manchus convinced Gen Wu Sangui to open the gates of the wall at the Shanhai Pass and allow them through.
As it weaves through nine northern provinces and municipalities, the Great Wall is actually a collective name for many originally unconnected castles and smaller walls and fortifications. It stretches to some of the country's most remote regions, making its exact length and condition difficult to keep track of.
There was consternation when China's first astronaut Yang Lewei revealed that he couldn't, in fact, see the Great Wall from space during his country's maiden manned space flight in 2003.
While space travel has debunked one myth about the wall, it may help give more accurate information about the structure as China plans to use satellites and other high-tech methods to check the length of the Great Wall and find ways to better protect it.
There are still sections being discovered - in some remote areas, bits were found as late as 2002. At the same time, weather erosion has also wiped away chunks of masonry from the structure.
Mao Zedong used to say "You're not a real man if you haven't climbed the Great Wall" and as millions of Chinese people get wealthy for the first time and are able to travel, the Great Wall is generally the first stop on their itinerary.
Mao's comments echo those of US president Richard Nixon, who exclaimed when he first saw the structure: "It sure is a great wall."
At Badaling, one of most accessible sections of the Great Wall from Beijing, thousands of visitors clamber over the ramparts, pursued by hundreds of hawkers selling everything from Tibetan carpets to camel rides to noodles.
There's even a Starbucks coffee house.
The stone walkways along the ramparts are worn smooth from millions of feet and nearly every brick has names scratched on them.
A total of 60,000 people climbed the Great Wall near here during the National Day holiday in October.
Cable cars bring tourists up the steep hills to the wall and half-marathons and 10km races are run along sections of the wall.
A spate of raves and rock concerts are taking their toll, and there was widespread outrage in the local media last year at reports from a dance party at the wall where partygoers, both westerners and Chinese, took drugs and had sex on the ramparts and urinated against it. Is nothing sacred, many asked.