Step outside the stone archway of Jianchunmen Gate in Ganzhou, and the ground beneath your feet begins to float. Here, the Dongjin Bridge stretches four hundred meters across the wide Gong River. It is a living survivor from the Southern Song dynasty, built between 1163 and 1173 under the direction of Hong Mai. Hong, a renowned scholar and the military prefect of the region, designed this floating highway to replace dangerous ferry crossings. His design kept the river open for trade and city defense.

The engineering relies on a flexible, modular system. Roughly one hundred wooden boats, divided into thirty-three groups, support a five-meter-wide deck of mature Chinese fir planks. Heavy iron chains, steel cables, and stone anchors secure the entire assembly to the riverbed. This allows the bridge to rise and fall naturally with the seasonal floods of the Gong River. During the busy days of river transport, crews would untie a section of the bridge twice daily—at 9:00 in the morning and 4:00 in the afternoon—swinging it open to let river traffic pass, preserving a centuries-old maritime schedule.

You can feel the history of this structure through direct physical sensations. Walking across, you experience a gentle, rhythmic swaying. The soles of your shoes press against the warm, weathered grain of the fir planks. The air carries the sharp scent of river water and fresh fish, sold by local fishermen who dock their small vessels directly against the floating deck. If you look closely at the hulls, you can see the sticky, protective sheen of tung oil and lime, applied by local shipwrights using traditional boatbuilding techniques to prevent dry rot.

Modern concrete highways replaced Ganzhou's other Song-era pontoon bridges in the late twentieth century. However, the community preserved the Dongjin Bridge, which became an officially protected heritage site when it was designated as one of the sixth batch of Jiangxi Provincial Key Cultural Relics Protection Units in 2018. Today, it remains a busy thoroughfare where commuters, school children, and visitors walk alongside fishermen. The ancient bridge continues to serve the daily needs of the city, bridging the gap between medieval engineering and modern life.