What does this number measure?
The French Ministry of Culture gives 275 m for the Pont du Gard's longest level. The comparison uses this present horizontal length, not the roughly 50 km route of the Nîmes aqueduct or its height of nearly 49 m. The side view depicts its three tiers; stonework and environmental details are interpreted.
Compare the stated dimensions
The comparison uses the number in each fact sheet: altitude, height, diameter, length or distance, depending on the reference. Two values in metres do not necessarily describe the same property.
Source and limitations
Current length of the upper tier, different from the reconstructed ancient extent and from the other tiers.
Pont du Gard: interpreted architectural elevation, not a photograph. The width of the upper tier provides the reference of 275 m; the stones, rocky supports and dimensions of the other tiers are not dimensioned by the drawing.