Luoyang Bridge — also called Wan'an Bridge — is one of the great engineering achievements of medieval China. At 1,200 metres long, it was the longest sea bridge in China when completed in 1059, built across a tidal estuary using an innovative technique that became the model for subsequent stone bridge construction. Governor Cai Xiang's use of oyster cultivation to cement the foundations was brilliant improvisation, but the engineering challenges he solved — large stone beams over tidal water, protective pillars against currents, uniform alignment across a wide estuary — represent centuries of accumulated knowledge.
The bridge is about five kilometres north of Quanzhou's old town and is easily reached by taxi. It remains in use for pedestrians and cyclists. The stone pillars are original Song-dynasty construction; the beams and parapets have been repaired repeatedly. A small museum at the north end explains the construction technique. The bridge is best seen at low tide when the engineering of the foundations is more visible, and at dawn before the day-trippers arrive. It is a UNESCO-inscribed site.