Gier Roman Aqueduct

This guide to the Gier Roman Aqueduct near Lyon follows the eighty-six-kilometer channel that carried water by gravity alone from a spring on Mont Pilat to Roman Lugdunum, through eleven tunnels and a fall of barely a meter per kilometer. It explains how Roman engineers handled the valleys gravity couldn't cross, forcing water into pressurized lead pipes laid side by side rather than trusting one wide pipe. Stand back to take in all seventy-two arches marching across the plateau in a single line.