Jiayu Pass, the largest and most intact pass of the Great Wall of China. The pass itself had been of strategic importance since the Han Dynasty and troops had guarded this area from then on. The Eastern and Western Towers were constructed. To complete its defence system a 50km long wall was piled up by 1536, which blocked the flat valley between the Black Mountain and the Wenshushan Mountain. Part of the wall also extended up the Heishan.
Because of years of disrepair, weathering and erosion, the structure of Jiayuguan Pass has shown varying degrees of foundation subsidence, wall cracking, paint stripping and other minor forms of damage. In order to protect this world cultural heritage site, the Chinese government allocated 2.03 billion yuan at the end of 2011 for a three-year project to repair and protect the Jiayuguan Pass, the Jiayuguan town and the neighboring parts of the Great Wall.