The Pont Saint-Esprit was commissioned by the Abbey of Cluny, and in 1265 the Pontist Brothers began to found the piers, after discussing their plans with Jean de Tessanges, Abbot of Cluny. Now, an earlier work of the Pontist Brothers, the Pont Saint-Bénézet at Avignon, was eighty years old in 1265, and his behaviour in the Rhône must have been a subject of interest to the successors of Bénézet. I conclude, then, that the Pont Saint-Esprit may be looked upon as a technical criticism of the earlier bridge, and it approves in all respects the work of St. Bénézet. Both bridges have relief arches for spate water, and when they are examined in bird’s-eye views, both have an elbow opposed to the current of the Rhône, and each suggests the image of a bridge of boats to which already I have drawn attention (p. 262). This image is rather more pronounced in the case of the earlier bridge, for the length of Bénézet’s piers, in the direction of the current, is enormous, being not less than thirty metres. For the rest, the Pont Saint-Esprit seems to have an enchanted size, his most confident historians giving neither the same dimensions nor the same number of arches. Men with tape measures have grown tired of their job, seemingly; and even in photographs some arches are omitted while others are blurred by distance. On my table is an excellent photograph: it takes in just a bit of the metal arch which, about fifty years ago, displaced two of the old arches and made a passage for boats. From this point to the elbow upstream, there are eleven arches; beyond the elbow there are six more, and the bridge is not complete. This is all the camera can do. According to Viollet-le-Duc, there are twenty-two arches in a length of about 1000 metres; the roadway is five metres wide. Larousse tells me, on the other hand, that the length is 738 metres, the width 5 metres 40, the number of arches twenty-six; and another great work of reference, published also by Larousse, gives 919 metres for the length, and says that among the twenty-five arches there are nineteen ancient ones. We ought to admire the variegated self-confidence of historians. But the main point is evident enough: the Pont Saint-Esprit is one of the longest stone bridges in the world. And the construction is truly marvellous. This was proved when a pier was pulled up to make room for the iron arch. The labour required was astounding, so excellent was the cemented masonry. But, of course, the bridge has passed through a good many changes to keep him in touch with the increase of traffic. In the seventeenth century he was still closed at both ends by strong gateways, while on the town side was a quite important defence of the fourteenth century, afterwards embodied in the citadel by which the river was guarded above-bridge. These defensive works have all gone, but their effect can be studied in “La Topographie de la Gaule,” where an engraving gives a good idea of their appearance.