In China's Yan Mountains stretches the Great Wall at Gubeikou, one of the most historically significant and difficult-to-reach sections of the Great Wall of China. This part of the wall once played a key role in protecting China from Mongol invasion and today stands as an untouched architectural feat—the last reconstruction work took place in 1567 and no renovations have been done since then.
Two hours from Beijing, the Great Wall at Gubeikou offers the opportunity for a relatively easy hike with picturesque views of the masonry stretching out to the east and west. Along the length of the wall are 143 ancient watch towers and three citadels, along with a number of other military constructions. While it's possible to explore this section on a long day trip from Beijing or as part of a single-day hike between Gubeikou and Jinshanling, it's more commonly visited as part of a multi-day guided hike of the wilder parts of the Great Wall.