The Pont du Gard
How did Roman surveyors, working with a water-level trough and a sighting frame, lay out a 50-kilometre water channel that falls only about a dozen metres end to end — and then carry it across a river gorge on three tiers of dry-laid stone that drop just 2.5 centimetres from one bank to the other?
mid-1st century CE (long attributed instead to c. 19 BCE) · Vers-Pont-du-Gard, Gard, Occitanie, FranceAdded September 2026