Photos

The Pont du Gard was built shortly before the Christian era (19 b.C.) to allow the aqueduct of Nîmes (which is almost 50 km long) to cross the Gardon river. The Roman architects and hydraulic engineers who designed this bridge, which stands almost 50 m high and is on three levels – the longest measuring 275 m – created a technical as well as an artistic masterpiece, inscripted ijn 1985 in the list of Unesco World Heritage sites.
The bridge was built from blocks of local stone (light yellow limestone that is easy to cut) from the Estel quarry, 500m upstream of the monument on the left bank of the Gardon.
Construction of the Pont du Gard was the major engineering element of the aqueduct and for three to five years, up to a thousand men would have been working on it all the time. The volume of stone required to make the bridge has been estimated at 21,000 cubic metres representing a total weight of some 50,400 tons. The bridge is therefore a brilliant assembly of very large stones that hold together without mortar.

The water-carrying upper conduit is said to be waterproofed applying a final layer of "quicklime slaked in wine, and mollified, in turn, with an admixture of fig juice and pork fat", a detail (referred by Pliny the Elder) that strongly struck my 9-years-old son...

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Technical details.
Even if one could not notice (and this was indeed my goal...) the picture is an HDR overlapping of three shots, necessary to counteract the strong light contrast from this POV.