At Jiumenkou in Suizhong County, the wall crosses the Jiujiang River. Eight piers divide the crossing into nine openings, giving the place its familiar name. The wall continues overhead while water has routes beneath it.
That arrangement states the builders’ problem clearly. A defensive line could follow a ridge, but a river could not simply be wished away. The crossing needed to preserve continuity above and passage below. The river channel is integral to the form of the fortification.
