Pont du Gard

The Pont du Gard is a three-tiered Roman aqueduct bridge over the river Gardon near Vers-Pont-du-Gard in southern France. Built in the first century CE, it carried a channel that brought spring water some 50 kilometres to the Roman colony of Nemausus, modern Nîmes. Standing about 49 metres above the river and some 274 metres long, it is one of the best preserved of all Roman aqueduct bridges.

Nemausus, a city of perhaps 50,000 people in the province of Gallia Narbonensis, had no convenient water source. The plains to the south and east lay too low, and the hills to the west were too rugged, so engineers looked north, to the Fontaine d'Eure springs close to Uzès. Although the two points are only about 20 kilometres apart in a straight line, the aqueduct had to swing round the wooded limestone hills of the Garrigues de Nîmes, and much of it ran underground in a covered stone channel. The total drop from source to city was small, and the engineers varied the gradient along the route to keep the bridge over the Gardon within a buildable height. Over the bridge itself the channel falls by only a couple of centimetres.

The bridge has three levels of arches set one above another, built of local shelly limestone from a quarry a short distance downstream. Most of the blocks, some weighing up to six tonnes, were cut so precisely that they were laid without mortar, and many still carry the masons' marks showing where they were to go. The water channel on the top tier was lined with stucco and a smooth coating to keep the flow unobstructed. The upper tiers bend slightly upstream; this was long thought to be deliberate, but a survey in 1989 found that it results from the stone expanding and contracting in the sun over the centuries.

The aqueduct was long attributed to Marcus Agrippa, the aide of Augustus, around 19 BCE, a link proposed by the archaeologist Émile Espérandieu in 1926. More recent excavations point to a later date. The builders had to bypass tunnels of Augustan date, and no coins older than the reign of Claudius (41 to 54 CE) were found in the outflow at Nîmes, so Guilhem Fabre and his team have argued that the system was finished around the middle of the first century CE, perhaps after about fifteen years of work by 800 to 1,000 labourers.

From the fourth century, as the Roman Empire lost its grip on the region, maintenance lapsed. Lime deposits and plant roots choked the channel, and the aqueduct had probably stopped working by about the sixth century, though parts may have stayed in use longer. The bridge itself survived largely because it remained useful as a crossing. In the thirteenth century the French crown granted the lords of Uzès the right to charge tolls on it, a right later transferred to the bishops of Uzès, who maintained the bridge in return. In the 1620s, during the wars between the royalists and the Huguenots, Henri, Duke of Rohan, had part of the second tier cut back so that his artillery could pass, seriously weakening it.

Local authorities repaired the bridge in 1703, and between 1743 and 1747 the engineer Henri Pitot built a road bridge alongside the lowest tier. French kings had long valued the monument as a link with imperial Rome: Charles IX visited in 1564 and Louis XIV in 1660. By the 1830s it was again in danger of collapse. Napoleon III took a close interest after visiting in 1850, and the architect Charles Laisné restored it between 1855 and 1858, replacing worn stone and strengthening the piers. Writers including Jean-Jacques Rousseau and Alexandre Dumas recorded their impressions, and travellers on the Grand Tour made it a regular stop.

UNESCO inscribed the Pont du Gard on the World Heritage List in 1985. It came through severe floods in 1958, 1998 and 2002. By the 1990s traffic and unlicensed buildings crowded its banks, and a four-year project begun in 1996 closed the area to vehicles and opened a new visitor centre in 2000. It is now one of France's most visited monuments, with about 1.4 million visitors reported in 2001.