The Panlongshan or "Coiling Dragon Mountain" Section of the Great Wall is one of the few sections that is open to tourists but hasn't as yet been officially restored, meaning it is one of the last remnants of the wild Great Wall. For this reason, parts of the wall are crumbling and vegetation peeks through the cracks, endowing this section with a certain ruined beauty.
If you want to visit this breathtaking section of the wall, you will probably need to dedicate at least a day or perhaps 2 days to get there first. You can either hire a car/taxi directly from Beijing, which will take just over two hours, or you can take public transport, which may take upwards of 4 hours. You'll first need to get the 980 Express bus from Dongzhimen Station in Beijing to Miyun (密云) and then transfer to 密25, which will take you to the small town of Gubeikou (古北口镇). You'll want to get off at the second stop in Gubeikou. For this reason, we'd recommend staying overnight either in Gubeikou or at one of the guesthouses near to the base of Panlongshan.
Gubeikou itself is a picturesque little town with plenty of history. It once served as a garrison town along the Great Wall and is littered with a number of small temples, as well as several old buildings. The town is currently being developed for tourism, so be sure to visit it as soon as possible before you lose the chance to see it at its most authentic!
Once you arrive at the entrance to Panlongshan, you can either go left or right. If you choose to go left, the views are incredibly beautiful, but you will only be able to hike for about 2 hours before you reach a dead-end, as this part of the wall becomes dangerous to the point of being impassable. Alternatively, if you go to the right, you can hike for about 2 hours along the wall itself, then take a 1 hour hike through the woods, which will eventually take you to the west entrance of the Jinshanling Section of the Great Wall. This means you can normally hike both sections of the wall in one day, although be advised that you will need to pay for a separate entry ticket to the Jinshanling Section.
If you're feeling peckish or dehydrated, there's usually a woman selling drinks and ice cream at the west entrance. If you can't find her, just walk a little further up the road and you'll find her shop, which sells ice-cold drinks, coffee, and some snacks.
Personally, we feel the best time to visit this section of the wall is either during spring, when the blossoms are in full bloom, or in autumn, so that you can admire the changing leaves. The weather during these seasons is particularly comfortable for hiking, whereas summer can be unbearably hot and winter can be too chilly.
If you want to truly head off-the-beaten-track and experience the Great Wall at its most wild, then this is definitely the section of the wall you should visit!