I plan to visit the great wall of China, starting from Badaling.
As a test to my stamina, I plan to hike along the wall, for as long and as far as I can, until I can't go further because either it's a tourist-nogo zone ( ie: some solders are posted there to prevent further trespassing), or because the section is completely reclaimed by forests and trees that no one can pass unless he is equipped with chainsaws or bulldozers or tanks.
How far I can go, and how much time I need to take?
You can walk the entire Ming Dynasty Great Wall it's only 6000 kilometers give or take a few and doesn't even take two years:
On Dec 2, 601 days after departing from the Wall's westernmost terminus, Gansu province's Jiayuguan, the 42-year-old stomped over the final brick of the final eastern watchtower, Liaoning province's Hushan.
I'm chinese, and I went to the Great Wall last year. I believe you can go to the top. But people mountain, people sea. Also, if you do not know the specific way to the great wall, you will pay at least 150 CNY from the last metro or bus station. But it seems there is a train which is fast and cheap and convenient to the great wall directly.
The first time, I did not know the way, so I didn't find the right way to the great wall. I went out in the morning and arrived at 17:00 at the great wall. The second time, I knew the way and went out in the morning, and arrived at 12:00 at the great wall, but I only spent 2 hours there. It's not a long time! Not long!! We 3 girls climbed just 1 hour up to the top and one hour down. Hope you enjoy your days in China.
From Wikivoyage on Badaling:
The hike is a challenge with plenty of steep hills, so once you get a bit into the wall the crowd thins quickly. It takes ~2-3h to hike the whole wall depending on your fitness/weather/crowd.
I've only been to the Great Wall in Beijing, which is a huge segment of the wall.
It would be fantastic if the Great Wall were just a single, fully connected really long and thin park. Unfortunately, this is not the case. There are instead a bunch (dozens?) of segments that are beautifully reconstructed, like in your picture. These are run as tourist attractions/natural parks by the governments, and are great for day trips. Generally, these well-built areas will have a definite starting and stopping point, and security guards.
Other parts will have never been maintained, and are also very interesting. Sometimes of these non-rebuilt areas are also organized as a tourist attractions, sometimes they are not. These are highly recommenced, if you have time. My favorite segment ran through the middle of a sheep farming village, and required that I walk through a small river. Very beautiful. I have seen camping there too.
Other parts are on private property and will not be accessible. I am very curious about the article in the answer by @chx; it would be great if there were detailed notes available.
