The Pont du Gard is an aqueduct in the South of France constructed by the Roman Empire, and located in Vers-Pont-du-Gard near Remoulins, in the Gard département .

Pont du Gard literally means bridge of the Gard (river). The Gard River, which has given its name to the Gard département, does not actually exist under this name. The river, formed by many tributaries, several of which are called Gardon, is itself called Gardon until its end.

Built on three levels, the Pont is 49 m high, and the longest level is 275 m (300 yards) long.
  • Lower level: 6 arches, 142 m long, 6 m thick, 22 m high
  • Middle level: 11 arches, 242 m long, 4 m thick, 20 m high
  • Upper level: 35 arches, 275 m long, 3 m thick, 7 m high
On its first level, it carries a road and at the top of the third level, a water conduit, which is 1.8 metres (6 ft) high and 1.2 meters (4 ft) wide and has a gradient of 0.4 percent.

It has long been thought that the Pont du Gard was built by Augustus' son-in-law and aide, Marcus Vipsanius Agrippa, around the year 19 BC. Newer excavations, however, suggest the construction may have taken place in the middle of the first century A.D; consequently, opinion is now somewhat divided on the matter. Designed to carry the water across the small Gardon river valley, it was part of a nearly 50 km (31 mi) aqueduct that brought water from the Fontaines d'Eure springs near Uzès to the Castellum in the Roman city of Nemausus ( Nîmes). The full aqueduct had a gradient of 34 cm/km (1/3000), descending only 17 m vertically in its entire length and delivering 20,000 cubic meters (5 million gallons) of water daily. It was constructed entirely without the use of mortar. The aqueduct's stones – some of which weigh up to 6 tons – were precisely cut to fit perfectly together eliminating the need for mortar. The masonry was lifted into place by block and tackle with a massive human-powered treadmill providing the power for the winch. A complex scaffold was erected to support the aqueduct as it was being built. The face of the aqueduct still bears the mark of its construction, in the form of protruding scaffolding supports and ridges on the piers which supported the semicircular wooden frames on which the arches were constructed. Various inscriptions are found across the surface, containing instructions used in construction. For example, "FRS II" ( frons sinistra II, Latin for "left face 2"), phallic symbols (intended to ward off bad luck), and graffiti left by builders throughout the ages. The upper levels of the bridge are slightly curved in the upstream directions, a fact long attributed to the engineers wanting to strengthen it against the flow of water, like a dam wall. However, a microtopographic survey carried out in 1989 showed that the bend is caused by the daily expansion and contraction of stones under the heat of the sun, by about 5 millimetres. Over the centuries, this process has produced the deformation witnessed now. It is believed to have taken about three years to build, employing between 800 and 1,000 workers.

Post Roman
From the fourth century onwards, its maintenance was neglected, and deposits filled up to two thirds of the conduit space. By the ninth century, it became unusable, and the people of the area started using its stones for their own purposes. However, the majority of the Pont du Gard remains impressively intact. From the Middle Ages to the 18th century, the aqueduct was used as a conventional bridge to facilitate foot traffic across the river, like its much smaller sister, the Pont de Bornègre. The pillars of the second level were reduced in width to make more room for the traffic, but this jeopardized the stability of the structure. In 1702 the pillars were restored to their original width in order to safeguard the aqueduct. In 1743, a new bridge was built by a French engineer Henri Pitot next to the arches of the lower level, so that the road traffic could cross on a purpose-built bridge. The aqueduct was restored in the 18th century, by which time it had become a major tourist site, and was restored again in the reign of Napoleon III in the mid-19th century. The outstanding quality of the bridge's masonry led to it becoming an obligatory stop for French journeymen masons on their traditional tour around the country (see Compagnons du Tour de France ), many of whom have left their names on the stonework. Markings left by the original builders can also be seen, indicating the positions in which the dressed stones were to be placed: for instance, FRS II (standing for frons sinistra II, or "front left 2"). This is a tradition that has been partly continued by modern visitors, often looking to make their own markings. In May 1940 a French pilot, Séraphin Civera, flew his plane through one of the arches. The Pont du Gard was added to UNESCO's list of World Heritage Sites in 1985. In 1998 the Pont du Gard was hit by major flooding which caused widespread damage in the area. The road leading up to it and the neighboring facilities were badly damaged, although the aqueduct itself was not seriously harmed. The French government sponsored a major redevelopment project in conjunction with local sources, UNESCO and the EU which concluded in 2000, pedestrianising the entire area around the aqueduct and greatly improving the visitor facilities, including establishing a museum on the north bank. The project has been criticized for its cost (€33 million) and for the perceived loss of natural beauty of the surrounding landscape and area. During the redevelopment it was not possible to walk through the conduit at the top of the aqueduct; however guided crossings are now provided by the museum. The redevelopment has ensured that the area around the Pont du Gard is now much quieter due to the removal of vehicle traffic, and the new museum provides a much improved historical context for visitors. The Pont du Gard is today one of France's top five tourist attractions, with 1.4 million visitors reported in 2001. The 19th century Roquefavour Aqueduct of the Canal de Marseille replicates the Roman architecture of the Pont du Gard.