Pont du Gard: part of the aqueduct of Nîmes, one of the most famous ancient monuments of France.
The Pont du Gard is a section of the forty-nine kilometer long aqueduct that once carried water from the Fontaines d'Eure source near Ucetia (modern Uzès) to the city of Nemausus (Nîmes), which is only seventeen meters lower. This means that the water has a gradient of exactly 1:3000. It was probably built in the third quarter of the first century, during the reign of Nero. This "bridge" across the ravine of the river Gard (or Gardon) is 275 meters long (at the top). The water conduit itself is forty-nine meters above the level of the river, and the capacity was about 20,000 m³/day.
A similar monument - shorter but still functioning - can be visited in Segovia in Spain. The museum of the Pont du Gard is one of the most beautiful in Europe.