councils (see Council of Arles), the rival of Vienne, for hundreds of years.
Roman aqueduct and mill
The Barbegal aqueduct and mill is a Roman watermill complex located on the territory of the commune of Fontvieille, a few kilometres from Arles. The complex has been referred to as "the greatest known concentration of mechanical power in the ancient world". The remains of the mill streams and buildings which housed the overshot water wheels are still visible at the site, and it is by far the best preserved of ancient mills. There are two aqueducts which join just north of the mill complex, and a sluice which enabled the operators to control the water supply to the complex. The mill consisted of 16 waterwheels in two separate rows built into a steep hillside. There are substantial masonry remains of the water channels and foundations of the individual mills, together with a staircase rising up the hill upon which the mills are built. The mills apparently operated from the end of the 1st century until about the end of the 3rd century. The capacity of the mills has been estimated at 4.5 tons of flour per day, sufficient to supply enough bread for the 6,000 of 30-40,000 inhabitants of Arelate at that time. Another similar mill complex existed also on the Janiculum in Rome. Examination of the mill leat still just visible on one side of the hill shows a substantial accretion of lime in the channel, tending to confirm its long working life.
It is thought that the wheels were overshot water wheels with the outflow from the top driving the next one down and so on, to the base of the hill. Vertical water mills were well known to the Romans, being described by Vitruvius in his De Architectura of 25 BC, and mentioned by Pliny the Elder in his Naturalis Historia of 77 AD. There are also later references to floating water mills from Byzantium and to sawmills on the river Moselle by the poet Ausonius. The use of multiple stacked sequences of reverse
