Introduction to the plank road: Xu Xiake, a famous traveler in the Ming Dynasty, wrote in his travel notes after visiting Shimen Pass: "As I tilted my head to look eastward, suddenly clouds burst out, revealing two pieces of green hibiscus, inserted into the ground, standing side by side and facing each other. The mountains are reflected on top of each other, and the shadows of clouds appear and disappear, which makes people jump. "Looking at the stone gate, it is very close. It is close to each other, and it is cut thousands of feet apart. The top and two ends are the same, and its roots can only hold a water... …The clouds and greenery on Shimen Cliff are split, and the cliffs are so tall that it’s really a wonder.”