Octagonal City, a millennium-old city lost in the secret realm of Ganja

Octagonal City is located 35 kilometers north of Labrang Town, situated on the river terrace of the Ganja Grassland. As the name suggests, Octagonal City has eight corners, but it is actually in the shape of a 'cross.' According to investigations and surveys by relevant archaeological experts, the preliminary conclusion is that Octagonal City, with its central axis aligned in the north-south direction, represents a typical urban style of ancient Chinese society. The thickness of its rammed earth layers and the spacing of the horizontal rows are completely consistent with those of Chang'an and Luoyang cities from the Han and Wei dynasties. Neolithic pottery shards are often found in the lower rammed earth layers of the city walls, and pottery shards from the Tang and Song dynasties appear in the upper layers. Combined with the Han tombs on the northwest highlands outside the city and the Wang Mang era coins unearthed, it is concluded that Octagonal City was built during the Han dynasty. The unique city wall structure of Octagonal City showcases the design and defensive features of ancient garrison cities. The castle's design breaks away from the past square or rectangular shapes, forming its own system, making it unique among the existing ancient cities in China. On May 25, 2006, the 'Notice of the State Council on Approving and Announcing the Sixth Batch of National Key Cultural Relics Protection Units' listed the ancient site of Octagonal City as the sixth batch of national key cultural relics protection units.