The Gier Aqueduct is the longest of the four aqueducts that supplied water to the city of Lugdunum.
The water conveyance system relied entirely on gravity, maintaining a constant, extremely shallow gradient over its entire length.
The site includes a complex pressurized siphon system used to cross deep valleys, a hallmark of advanced Roman hydraulic engineering.
Construction utilized the opus reticulatum technique, characterized by diamond-shaped tuff bricks set into concrete cores.
The aqueduct provided an estimated 10,000 to 15,000 cubic meters of water per day to the city of Lugdunum.
The Gier Roman Aqueduct in Chaponost, part of the extensive Gier system, once transported water across 86 kilometers to the Roman city of Lugdunum, modern-day Lyon. The Chaponost site features the 'Plomb' section, which contains 72 preserved stone arches standing up to 15 meters high. Built in the 1st century AD, this hydraulic engineering marvel utilized a precise gravity-fed slope of approximately one millimeter per meter. The arches were constructed using large limestone blocks and opus reticulatum stonework. This segment is the longest remaining above-ground portion of the four major aqueducts that supplied ancient Lyon. Visitors can walk along the path directly beneath and alongside the remaining masonry structures. Information panels situated along the site detail the historical operation of the siphon systems and the maintenance challenges faced by Roman engineers.
The perspective from the fields adjacent to the arches provides the best angle to capture the full row of standing stone structures.
Wear sturdy walking shoes to navigate the unpaved paths around the arch foundations.
Bring a water bottle, as there are no facilities directly on the arch site itself.
Visit during clear weather to clearly observe the structural details and stonework of the arches.
Attempting to climb the arch structures, which is both dangerous and prohibited to ensure site conservation.
Do not climb on the ancient masonry or remove stones; remain on designated pedestrian paths to preserve the structure.
