This section of the Great Wall of China is known as Mutianyu. It is about 70km outside of Beijing and is generally thought to be less crowded than the closer Badaling section. My wife and I didn’t visit the Badaling section so I can’t speak in to how crowded that was, but Mutianyu was still crowded in spots, even in the off-season.
China has done a good job of restoring this section to reflect the original condition of the wall. We hiked to Mutianyu from the Jiankou section, which is completely unrestored. It’s dilapidated condition is death-defying in its traverse so after two days of hiking along the broken and overgrown area the pristine conditions of Mutianyu were a welcomed change for us. They have also made Mutianyu very accessible via cable car and even a luge type slide (we call them alpine slides in the States) for the way down. We took the slide on the way out, but I wouldn’t do it again as too many people were going so slow that it didn’t make it much fun or provide an adrenaline rush, as expected. It was a let down and too expensive for the experience we got.
Don’t be fooled by all the modern convinces. This section of the Great Wall is still in a mountainous terrain and can be a strenuous hike with uneven steps. Come prepared to do some uphill climbing, even if you do take the cable car up.
Making your way to the Mutianyu section from Beijing is fairly easy via public transport, but make sure you have good translations. I would recommend printing instructions in Mandarin (with English translation on the back) so you can show them to locals and they can point you in the right direction. Unless things have changed since 2014, you can make your way to the Dongshimen Bus Station in Beijing and catch Bus No. 867 straight to Mutianyu. Dongshimen is a major subway stop. The Beijing subway system is massive and crowded, yet well laid out and fairly easy to navigate as everything is listed in multiple languages. It may seem overwhelming at first, but just leave yourself some extra time to make sure you are going the right direction before you step onto a train and you will be fine. If you do get lost, it just adds to the adventure.