
There is in fact no one Great Wall Of China. What we think of as the Wall is actually a series of walls built over centuries using different techniques and today in various states of repair.
The Great Wall Of China was started by
the first Emperor of Qin, Qin Shi Huang, he of Terracotta Army fame in 214BC to protect the newly united China from attacks from the north. Much of what we know today of the wall was built much later, between 1569 and 1583, as the Ming dynasty struggled to keep the Mongols at bay.
Thousands of labourers, many slaves, died during the building of The Great Wall, their bodies often buried in the Wall itself while it was under construction.
Today the Wall serves a much more peaceful function, both as an iconic symbol of China's past glories and as a major tourist attraction.
Much of the Great Wall outside of the tourist specific sections is badly maintained and can be dangerous so it is best to stick to the beaten track, busy though it will be.
If you are visiting Beijing, you will be within travelling distance of the Great Wall. Day trips to Badaling and Juyongguan are the most numerous, but since they are closest to Beijing they are also the busiest.
Mutianyu, around 60 miles North East of Beijing, is also close to the capital, but is slightly less crowded. That's probably because the climb to the Wall is steeper than at Badaling, but there is a cable car that will take you up. Here you can walk along part of the Great Wall, through ancient watch towers, and marbvel at the sheer expanse of the structure as it snakes its way through the hills.
Gubeikou, Jinshanling and Simatai are a bit further from Beijing (about 80 miles) than the sections above, but the extra time it takes to get there is rewarded with a very significant reduction in crowding and tourist traps. The most authentic part of the Wall is at Simatai as it is of original construction - unlike Badaling.
You will need to wear comfortable walking shoes and you are advised to take bottled water with you and anything else you may need for the day as shops are few and far between. Remember too that the Summer months can be blistering hot and the Winter months bitterly cold.