Short answers, pulled from the story.
The Pont du Gard was built in the first century AD. Construction has traditionally been credited to Marcus Vipsanius Agrippa around 19 BC, but excavations led by a team under Guilhem Fabre place its completion around the middle of the 1st century AD, between 40 and 60 AD. It is believed to have taken about fifteen years to build.
The Pont du Gard stands approximately 49 metres above the river Gardon at low water and is 274 metres long. Its width ranges from 9 metres at the base to 3 metres at the top level.
The aqueduct carried an estimated 40,000 cubic metres of water per day to the city of Nemausus, modern-day Nîmes. The journey from the Fontaine d'Eure spring to the castellum divisorum in Nîmes took nearly 27 hours.
The Pont du Gard was added to UNESCO's World Heritage List in 1985 on the criteria of human creative genius, testimony to cultural tradition, and significance to human history. The UNESCO description calls it a technical as well as artistic masterpiece.
The blocks were precisely cut from local Pierre de Vers limestone and fitted together by friction and gravity alone, without mortar or metal clamps. The structure contains an estimated 50,400 tons of limestone; some individual blocks weigh up to 6 tons. Many blocks were inscribed with their required positions to guide assembly.
In the 1620s, Henri, Duke of Rohan, had one side of the second row of arches cut away to about a third of their original thickness to create space for his artillery to cross during the wars between French royalists and the Huguenots. This seriously weakened the bridge and contributed to the deterioration that required major repairs in 1703.