Pont du Gard

Geography and history

The construction of the aqueduct has long been credited to Marcus Vipsanius Agrippa around 19 BC, but newer excavations suggest construction may have taken place between 40 and 60 AD.^[2] A team led by Guilhem Fabre has argued the aqueduct was completed around the middle of the 1st century AD, taking about fifteen years to build with 800 to 1,000 workers.^[3] The Pont du Gard remained largely intact because it was used as a toll bridge across the valley.^[4] The city of Nemausus (modern Nîmes) presented challenges for water provision because water sources on the southern and eastern plains were situated at elevations too low for gravity-fed flow, while the terrain to the west posed insurmountable engineering obstacles.^[5]

The sole viable option involved sourcing water from the northern region surrounding Ucetia (present-day Uzès), an area characterized by natural springs.^[5] Water from the Fontaine d'Eure springs, located near Uzès, was conveyed by the Nîmes aqueduct to the castellum divisorum, the distribution basin, in Nemausus.^[6] Although the direct distance between the spring and the city is roughly 20 km, the aqueduct's path meanders for approximately 50 km to navigate around the Garrigues de Nîmes.^[6] The elevation of the Fontaine d'Eure is 76 meters above sea level, a mere 17 meters higher than the distribution basin in Nîmes, yet this difference provided an adequate slope for consistent water flow.^[7]

The overall slope of the aqueduct averages a ratio of 1 in 3,000, which is considerably gentler than the typical gradient found in other Roman aqueducts.^[7]

What the cited sources add

The same source notes that the aqueduct supplied the city with around 40,000 m3 of water a day that took nearly 27 hours to flow from the source to the city.^[8][9] According to the "Encyclopedia of architectural and engineering feats", the stone blocks were cut with such precision that they were assembled using only friction and gravity, making mortar unnecessary.^[10][9] The work "Divine domesticity" describes the conduit's walls as being made of dressed stone and its floor of concrete, with both surfaces finished in a stucco that contained tiny fragments of pottery and tile.^[11][12] That same book explains that after the 4th century, the aqueduct fell into disrepair because a series of invading groups caused instability in the region, leading to a lack of maintenance.^[11][12]

"Southern France" recounts that the Pont du Gard was preserved because it functioned as a toll bridge, and that during the 13th century, the French monarch granted the seigneurs of Uzès the authority to collect tolls from people crossing it.^[4][13] The same source indicates that this toll-collecting right was subsequently transferred to the Bishops of Uzès, who, in exchange, were tasked with keeping the bridge in proper condition.^[4][13]