Really only of interest to dedicated bike riders, this ruin of a bridge is way off the beaten track, about 10km west of Salavan and then 10km north. The 150m-long bridge was blown up by American bombers in 1968 due to its position on a supply branch of the Ho Chi Minh Trail. Only some concrete supports and a part of the steel span remain. The contrast between heavy war damage and the peaceful setting makes it quite interesting.
The bridge is named after its builder, the 'Red Prince' Souphanouvong, who was a trained engineer.
You can take a ferry (10,000K) to visit the other side; in dry months you can just walk across the river.
Pretty well the only way to get here is by motorcycle. You can continue on to Toumlan, though there are lots of missing small bridges, so enquire in Salavan before attempting this route in the rainy season. The trip is interesting as it affords a beautiful drive following the mountains of the Se Ban Nuan NPA.