An Excursion to the Pont du Gard Aqueduct ~ Afternoon, October 11, 2019

An Excursion to the Pont du Gard Aqueduct ~ Afternoon, October 11, 2019

After another delicious lunch in the Aquevit Terrace, we met Camile, our guide for the excursion to the Pont du Gard Aqueduct.

The Pont du Gard is an ancient Roman aqueduct bridge built in the first century AD to carry water over 31 miles to the Roman colony of Nemausus (Nîmes). It crosses the Gardon River near the town of Vers-Pont-du-Gard in southern France. The Pont du Gard is the highest of all Roman aqueduct bridges, and one of the best-preserved. 

The bridge has three tiers of arches, stands 160 feet high, and descends a mere inch – a gradient of only 1 in 18,241 – while the whole aqueduct descends in height by only 41 feet over its entire length, indicative of the great precision that Roman engineers were able to achieve using simple technology.

The aqueduct formerly carried an estimated 8,800,000 imperial gallons of water a day to the fountains, baths, and homes of the citizens of Nîmes. It may have been in use as late as the 6th century, with some parts used for significantly longer, but a lack of maintenance after the 4th century led to clogging by mineral deposits and debris that eventually stopped the flow of water.

After the Roman Empire collapsed and the aqueduct fell into disuse, the Pont du Gard remained largely intact due to the importance of its secondary function as a toll bridge. For centuries the local lords and bishops were responsible for its upkeep, in exchange for the right to levy tolls on travelers using it to cross the river. Over time, some of its stone blocks were looted, and serious damage was inflicted on it in the 17th century. It attracted increasing attention starting in the 18th century and became an important tourist destination. It underwent a series of renovations between the 18th and 21st centuries, commissioned by the local authorities and the French state, which culminated in 2000 with the opening of a new visitor center and the removal of traffic and buildings from the bridge and the area immediately around it. Today it is one of France's most popular tourist attractions and has attracted the attention of a succession of literary and artistic visitors.

The first level of the Pont du Gard adjoins a road bridge that was added in the 18th century. The water conduit is about 6 feet high and 4 feet wide and is carried at the top of the third level. The upper levels of the bridge are slightly curved in the upstream direction. 

The Pont du Gard was constructed largely without the use of mortar or clamps. It contains an estimated 50,400 tons of limestone with a volume of some 740,000 cubic feet; some of the individual blocks weigh up to 6 tons.  

The builders would have made extensive use of cranes and block and tackle pulleys to lift the stones into place. Much of the work could have been done using simple sheers operated by a windlass. For the largest blocks, a massive human-powered treadmill would have been used; such machines were still being used in the quarries of Provence until as late as the start of the 20th century.