For Great Wall walkers, Badaling is the beginning. Then Mutianyu and Jinshanling. After that, the wilds of Jiankou, and you're probably feeling pretty darn intrepid. Congratulations, you've conquered 0.001% of the Ming Dynasty Great Wall. Ready to progress? This is the way I plan a Great Wall hike. You will need: Google Earth. A phone with internet and GPS. Rudimentary Chinese. A taxi or driver (or car). A friend. The Great Wall Forum. Clothing that covers your arms and legs. Water. Luck.
First thing to do is to figure out your hike (this post is presuming it's a day hike). Open Google Earth, and find the Great Wall. The GPS coordinates of many of the major (and minor) sections can be had here at the Great Wall Forum, listed in English according to province and section. Grab a set of coordinates as your starting point, and then just fly, fly, fly. Hover over the Wall until you find a bit that looks good. I like to drop pins on sections that seem geologically dramatic and are geographically relevant to where I am, or where I can get to (like a train station or small city, something likely to have a taxi company).
Pins are just the beginning. There are all sorts of icons you can throw down, but best of all is the path tool, which you can drag anywhere you like. This lets you trace the exact path of the Great Wall and measure distance accurately, which is really important. If you're going fully wild and uncharted, keep your day hike under 7km. And, of course, never hike alone. Strange as it might seem to non-Chinese, the Great Wall is largely uncharted territory to the general public and its location beyond a handful of tourist sections is only known by people living nearby, usually farmers.
So, taking a real, actual example of a hike I did in October 2015, the next step is the brilliant elevation profile feature. First I used Google Earth to choose a stretch of wall that looked enticing (for me the criteria is lofty, dramatic, unrestored, but within sensible range of civilisation), then I put down the red line on the map above using the path tool. Next, by selecting the elevation profile of that path, it gives me the red graph under the map. This is a cross-section of the path I have selected; it shows the elevation, incline and the really steep bits to avoid.
Looking at that elevation profile, I definitely want to avoid the crazy steep bit in the final third. Actually, the dip just after that could be a good starting point. There are two reasons why. First, by looking at Google Earth I can see an obvious access point on to the Wall here via a valley that starts from a marked road (indicated above with the blue pin). Secondly, about 6 km east, the wall drops down into a village which is actually the beginning of a lesser-known restored Great Wall section, Baiyangyu (White Sheep Valley).
Here's the elevation profile for just my selected hike, starting from the road, and it looks pretty good. A fair bit of climbing, but nothing crazy steep, either up or down. And again, the key thing is, I've got a start point reachable by road (you will have to direct the driver there via GPS - see above: phone), and a known end point (in this case the beginning of a touristed Great Wall section), so you can tell the same driver to go there and wait for you several hours later. (And sound the alarm if you don't come down by nightfall, potentially). That's the plan, anyway...
The reality, on the other hand... This terrifying quarry greeted us at the beginning of the hike. Not the kind of place you want to be. It didn't look this big on Google Earth, but the taxi had already dropped us off a kilometre or so back because the road was getting too rough for a car. It looked like the end of our hike before it had begun, but a worker drove past in a van, took pity on us, and gave us a lift through the quarry. See above: luck.
This is not the Great Wall, obviously. It's actually underneath the exact bit of mountain road where I'd dropped the blue pin and planned to start of hike. We were lucky, in a sense, that we did start in that quarry, because it didn't look easy to get down from this high section of bridged road and into the valley. Again see above: luck.
Once in the valley I knew with confidence that I was on my Google Earth path, and after a while, we got our first glimpse of watchtowers amid the autumn colours. What this photo doesn't show is that you simply cannot walk on these sorts of mountains if there is no trail. From a distance the foliage looks manageable, but the thorns are almost impenetrable (see above: clothing that covers your arms and legs). The trail faded out about 15 metres from the right hand watchtower, and it took us half an hour to get to it. That's a speed of 50 cm per minute, resulting in plenty of cuts and scratches.
The moral here is: never, ever leave the trail or path. Fortunately, along the Great Wall (at least almost all the wild sections I have hiked) the trails are marked with red ribbons tied to branches. It does mean that you can't just barrel down the hill when you've had enough hiking though, you better find access paths or shepherd trails, or just go back the way you came, otherwise you might get into trouble.
That's more like it! Our first stunning Great Wall vista of the day. In fact, we joined the Wall from the access valley somewhere in the bottom right of the photo, and this picture is facing west. That means this dramatic stretch of Wall is that crazy steep bit we were smart enough to avoid thanks to Google Earth. It's nice to photograph and admire, less fun to climb (especially downwards).
Something else to stress is that Google Earth will never reveal exactly how dramatic your hike will be. For example, during this stretch, the wall became natural rock along a sheer ridge line with stunning views and steep drops either side. Remember: wild wall hiking is risky. Loose rubble, unstable structures, limited access on or off the wall. It was supposed to be for defense, after all. See above: friend / water.
Other things you can do to keep safe(r): Hike in the warmer months. That way, if you have to spend an unscheduled night in a watchtower, you won't freeze, and you can set off again at first light. Bring a phone charger or portable battery with you. Keep your day hikes under 7km. Have a "civilised" end point in mind, like a village or commercial Great Wall section. And just go easy.
This unique watchtower is called Shenweilou (神威楼 - invincible might tower), an unusually well-fortified tower that is reasonably well documented. I knew via reading online (see above: Great Wall Forum) that it was almost at the end of my hike, and so I had a definite 'point' to aim for. The sight of this beauty from above was welcome relief (in fact, by then we could already see the road in the valley down below).
When you're ready to plan your own wild great wall hike, register at the Great Wall Forum and grab some tips and directions from the folks there, and be sure to share your own trips and knowledge too. Remember too that the wild Great Wall, however neglected, is a protected, technically private national monument. Do your bit; pick up other people's trash as you go, try to avoid disturbing loose rubble. Check out some more info on Great Wall heritage preservation (in English) here.