The Aqueduct of the Gier (French ''Aqueduc du Gier'') is an ancient

Roman aqueduct The Romans constructed aqueducts throughout their Republic and later Empire, to bring water from outside sources into cities and towns. Aqueduct water supplied public baths, latrines, fountains, and private households; it also supported min ...

probably constructed in the 1st century AD to provide water for

Lugdunum Lugdunum (also spelled Lugudunum, ; modern Lyon, France) was an important Roman city in Gaul, established on the current site of Lyon. The Roman city was founded in 43 BC by Lucius Munatius Plancus, but continued an existing Gallic settle ...

(

Lyon Lyon,, ; Occitan: ''Lion'', hist. ''Lionés'' also spelled in English as Lyons, is the third-largest city and second-largest metropolitan area of France. It is located at the confluence of the rivers Rhône and Saône, to the northwest of ...

), in what is now eastern

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

. It is the longest and best preserved of four Roman aqueducts that served the growing capital of the

Roman province The Roman provinces (Latin: ''provincia'', pl. ''provinciae'') were the administrative regions of Ancient Rome outside Roman Italy that were controlled by the Romans under the Roman Republic and later the Roman Empire. Each province was rule ...

Gallia Lugdunensis Gallia Lugdunensis (French: ''Gaule Lyonnaise'') was a province of the Roman Empire in what is now the modern country of France, part of the Celtic territory of Gaul formerly known as Celtica. It is named after its capital Lugdunum (today's Lyon) ...

. It drew its water from the source of the Gier, a small tributary of the Rhone, on the slopes of

Mont Pilat Mont Pilat or the Pilat massif is a mountainous area in the east of the Massif Central of France. Name The origin of the name "Pilat" is uncertain. The word may have a Latin origin (''Mons Pileatus''). Another legend says that the body of Pontiu ...

, south-west of Lyon. Following a sinuous path, at the aqueduct of the Gier is the longest known of the Roman aqueducts. Its route has been retraced in detail, following the numerous remains. Leaving the uplands of the Massif du Pilat, department of the Loire, the aqueduct hugs the surface relief and crosses the department of the Rhone, passing through Mornant, Orliénas, Chaponost and Sainte-Foy-lès-Lyon to terminate at Lyon. In its extent, it draws upon the whole repertory of Roman techniques of aqueduct building, taking a slope that averages 0.1%, or a meter every kilometer. There are of covered ditches laid with a concrete culvert high and wide, which is sunk as deep as beneath the land surface. The aqueduct passes through 11 tunnels, one of which, near Mornant, is in extent. Access for cleaning and repairs was through manholes at distances. There are some thirty stretches in the open air. There are ten stretches raised on walls and arches, which provide the most spectacular visible remains of the aqueduct (''illustrations''). Four

inverted siphon A siphon (from grc, σίφων, síphōn, "pipe, tube", also spelled nonetymologically syphon) is any of a wide variety of devices that involve the flow of liquids through tubes. In a narrower sense, the word refers particularly to a tube in a ...

tunnels cross the particularly deep and wide river valleys of the Durèze, the Garon, the Yzeron and the Trion on pipe bridges raised on high arches. In these, water filled a sunken tank tower (''

castellum A ''castellum'' in Latin is usually: * a small Roman fortlet or tower,C. Julius Caesar, Gallic War; 2,30 a diminutive of (' military camp'), often used as a watchtower or signal station like on Hadrian's Wall. It should be distinguished from ...

'') on the brim of a slope. The tank effected a transition between open channel flow and a lead pipeline. From the ''castellum'' water was carried, now pressurized, in a set of airtight lead pipes laid side by side, with

solder Solder (; NA: ) is a fusible metal alloy used to create a permanent bond between metal workpieces. Solder is melted in order to wet the parts of the joint, where it adheres to and connects the pieces after cooling. Metals or alloys suitable ...

ed joints, down the valley slope, across a bridge spanning the river—whose piers and arches are the most notable remains of the system—and up the facing slope, to a tank slightly lower than the head tank, losing just a little

hydraulic head Hydraulic head or piezometric head is a specific measurement of liquid pressure above a vertical datum., 410 pages. See pp. 43–44., 650 pages. See p. 22. It is usually measured as a liquid surface elevation, expressed in units of length, ...

in the process. The inverted siphons obviated the bridging of deep valleys with arcade upon arcade of arches, as at

Pont du Gard The Pont du Gard is an ancient Roman aqueduct bridge built in the first century AD to carry water over to the Roman colony of ''Nemausus'' ( Nîmes). It crosses the river Gardon near the town of Vers-Pont-du-Gard in southern France. The Po ...

, which marks the limit of such a system.

Date

The Gier aqueduct was built in a single great campaign, since no part of it could have served until it was completed; it must have taken years. The aqueduct of Giers was dated by Germain de Montauzon to the reign of

Hadrian Hadrian (; la, Caesar Trâiānus Hadriānus ; 24 January 76 – 10 July 138) was Roman emperor from 117 to 138. He was born in Italica (close to modern Santiponce in Spain), a Roman ''municipium'' founded by Italic settlers in Hispania ...

in the early 2nd century AD, but, as James Stephen Bromwich points out, its reticulated stonework (''

opus reticulatum ''Opus reticulatum'' (also known as reticulate work) is a facing used for concrete walls in Roman architecture from about the first century BCE to the early first century CE. Facings are a type of polygonal masonry used to apply a smooth finish to ...

'') was characteristic of the later 1st century BC and the first half of the 1st century AD, rather than of later masonry.Date revision was suggested by Jeancolas, ''JEAR'' 183, noted by Hodge 2002:435 note 10. In addition he notes that a recently excavated public fountain on the hill of Fourvières, datable about 50 AD could not have been supplied with water until the Giers aqueduct was complete.

Gallery

File:Aqueduc du Gier-Saint Maurice sur Dargoire-Pont de Jurieux.JPG, Arch of the aqueduct at Saint Maurice sur Dargoire showing ''

'' File:Aqueduc du Gier-Chaponost-Plat de l'Air-réservoir et rampant siphon de l'Yzeron.JPG, Chaponost, Plat de l'Air, headertank of the Yzeron inverted siphon Image:Aqueducchapo01.JPG, Vestiges of the Roman aqueduct in Chaponost File:Aqueduc du Gier-Mornant-Pont du Mornantet.JPG, Aqueduct of Gier at Mornantet

Notes

External links

In French:
ARCHEOLYON: Les Aqueducs Romains de LYON , l' AQUEDUC ROMAIN du GIER
- extremely detailed information, including detailed topographic maps of the whole route.
Lyon Historique: Tracé de l’aqueduc du Gier sur Google Earth (format kml)
- Google Earth trace of the whole route. * French Wikipedia: Aqueduc du Gier {{DEFAULTSORT:Gier, Aqueduct Of The Buildings and structures in Loire (department) Buildings and structures in Rhône (department) Roman aqueducts in France Ruins in Auvergne-Rhône-Alpes