France happens to be rich in fine relics of Roman bridge-building. Among her antique monuments there are remains of three aqueducts, at Fréjus and Lyon and Luynes; and every pontist has seen photographs of the aqueduct at Lambèse, in the department of Constantine, Algeria. At Vaison, in Vaucluse, over the river Ouvèze, we find an important Roman bridge, built on two rocks, with a single arch not less than thirty metres in span; and along one embankment is a range of tall and narrow arches that start out from the abutment of the bridge. The Pont de Vaison is not in all respects representative of the best Roman work, for its voussoirs, instead of being rimmed and extra-dossed, are fitted into the spandrils (p. 282). I do not know the date of this bridge, but Vaison descends from a famous Roman town, Vasio by name, mentioned by Mela (ii. 5) as one of the richest towns of the Narbonensis. It is common knowledge--or it should be--that the Romans adorned some of their bridges with a triumphal arch; and it happens, by rare good fortune, that France owns a small example of this Roman pride. It is the Pont Flavien at Saint-Chamas, which in a single arch, forty-two feet wide, spans the rocky bed of the Touloubre. At each entrance there is a triumphal arch seven metres high, flanked at each side by two Corinthian pilasters, upon the summit of which the entablature rests. There is a stone lion at each extremity of the entablature; it stands rampant and looks out into the open country, as if to symbolise for ever the wakeful power of Roman thoroughness. Only one of the four lions belongs to Roman workmanship; the others are much younger, and their proportions are bigger. This bridge, again, which I believe to be unique, bears an inscription, from which we learn that it was founded by a certain L. Donnius Flavus, a flamen of Rome and of Augustus. But the name Augustus was a title of veneration given by custom to all the Cæsars, so that Donnius Flavus and his bridge have uncertain dates. And now we will take a devious walk along some Roman roads through Gard-Hérault, to see what we shall find in the way of antique bridges. From north-east to south-west the region is crossed by the Via Domitiana, which runs from Lyons to the Pyrenees, going over the Rhône at Arles, and passing by Nîmes, Pont Ambroise, Substantion, Saint-Thibéry, Béziers, and Narbonne. At Pont Ambroise the river Vidourle is partly spanned by the ruins of a very picturesque Roman bridge, but its points of interest belong to an earlier chapter (p. 82). Near Castelnau, or Substantion, the Via Domitiana crossed the river Lez by a bridge now wholly destroyed; its abutments can be seen when the water is low, but they add nothing to our knowledge of Roman masonry. In mediæval times this bridge was called the Pont Lairou, Lero being the Latin name of the river Lez.