My favorite attraction—Yanmen Pass—I highly recommend hiring a local guide. Many of the defensive fortifications are difficult to understand on your own, especially the distinctive barbican of Yanmen Pass. Its layout differs from ordinary passes; after a guide explains the defensive logic of "catching a turtle in a jar," the experience of walking inside is completely different.
The most striking impression is how the pass separates two climates. Standing in the fortress and looking towards the inside and outside, the difference in the state of the trees is very obvious. Inside the pass is relatively warm and humid with more lush vegetation; outside, it's windy, cold, and the vegetation is withered. Seeing it with your own eyes, you truly understand why the ancients said Yanmen Pass divides north and south—it wasn't an exaggeration.
The entire scenic area stretches along the mountain ridge. Just looking at the stone tablets can be overwhelming. A guide will connect the historical battles and the changes in the ancient road, explaining the function of each point. To truly understand this first pass of China, a guided tour is essential; I recommend allowing ample time to explore at your own pace.