On 8 June 1839 the rock spur carrying the right abutment gave way, perhaps in an earthquake, and took the central arch down with it. Until that day the Roman bridge over the Cillian had worked without interruption: one of the most remarkable feats of engineering along the via delle Gallie, crossing the gorge of the torrent on a single round arch.
What to see
What is left is the springing of the arch, the eastern abutment and one blind archlet, which is enough to read how it was built. The bridge ran over 49 metres long and carried a roadway 4.64 metres wide, sheltered from the wind by high parapets and lit by small rectangular windows; the main arch had a span of 9.71 metres and its abutments rested straight on the rock of the gorge. On either side, two symmetrical stretches set at an obtuse angle joined the bridge to the road, with blind archlets faced in brick and, downstream, reinforcing buttresses. The facing alternates stone slabs and stone chips, mostly green.
Visiting
A second collapse came in 1907, when the western arch failed after water infiltration; in 1939 a broad restoration consolidated what remained. You reach it from the centre of Saint-Vincent, not far from the parish church.
Our editors' tip
This is a ruin, not a bridge: anyone hoping to walk across will be disappointed. It is worth the detour, though, to grasp how much work it took to carry a consular road through a gorge like this one.