Why it looks like this

The old city of Ganzhou occupies the point of land where the Zhang and Gong rivers meet to become the Gan, the river that named Jiangxi province's shorthand. Its Song-era brick walls still line the riverbanks.

The hidden marvel is underground: the Fushou ditches, a drainage network engineered in the Song dynasty roughly nine centuries ago, still works — locals note that the old town rarely floods even when modern districts do. The street pattern above follows the same ancient logic.