A bridge for water
The Pont du Gard was never meant for traffic. It is one section of a Roman aqueduct 50 kilometres long, built around the middle of the first century CE (about 50 CE, under Claudius or Nero) to bring water from the Eure spring near Uzès to Nemausus, the Roman colony that is now Nîmes. Water in an aqueduct moves by gravity alone, so the whole channel had to fall evenly from source to city: on average, 25 centimetres per kilometre, less than the length of a school ruler over the distance of ten football pitches.
Then the line met the gorge of the Gardon. Going down to the river and back up would have broken the slope, so the engineers took the channel straight across, at the height it needed to keep. That height was 48.77 metres above the river, about as tall as a sixteen-storey building.
Three tiers, unequal on purpose
The bridge rises in three levels of arches: 6 on the bottom tier, 11 in the middle and, originally, 47 small arches on top, carrying the channel along a gallery 360 metres long. The arches are not all the same. The lower arch over the river spans 24.52 metres, wider than those at the ends (21.87 metres), to let floodwater through, and the piers carry projecting spurs, which UNESCO calls “lips”, built to resist high water. The Gardon floods suddenly and violently, and the Roman builders designed the bridge around it. The whole structure weighs about 50,000 tonnes.
Building it took about five years and nearly a thousand men. Most of the stone came from the Estel quarry, about 600 metres downstream, which still survives. On the lower arches, the voussoirs are set in separate rings side by side, and many blocks still carry the marks the masons carved to show where each one went.
How much water?
Between 30,000 and 40,000 cubic metres a day, according to the site’s managers, enough to fill twelve to sixteen Olympic swimming pools. The aqueduct worked for about five centuries, and then the bridge started a second life.
How did it survive?
By being useful. In the Middle Ages people crossed the river on it, and to make room for a path they cut away half the thickness of the piers of the second tier, which put the whole bridge at risk. The structure also lost many stones, and twelve arches of the top tier, on the upstream side, are gone, so the top tier now runs for about 275 metres. Repairs came in 1699-1702, when the piers were mended and corbels were added to carry a road, and in 1746 the engineer Henri Pitot added a separate road bridge against the lower tier, matching the old stonework as closely as he could. Traffic moved there and left the Roman bridge alone. In 1985 the Pont du Gard became a UNESCO World Heritage Site.
Where to see it
The Pont du Gard stands at Vers-Pont-du-Gard, in the Gard department of southern France, on the road between Uzès and Nîmes. Opening hours and ticket prices change by season, so check the official Pont du Gard website before you go.
Sources
- UNESCO World Heritage Centre, “Pont du Gard (Roman Aqueduct)” (344).
- Pont du Gard official site, “History” and “The monument”; Estel quarry.
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