Barbegal
About
Sixteen waterwheels arranged in two rows down a hillside at Barbegal drove what is considered the largest concentration of mechanical power in the ancient world, grinding flour for a small city. A dedicated aqueduct branch fed the wheels in sequence, each turning a pair of millstones before passing water on. Carbonate deposits point to that branch being built around 120 to 130 CE, just after Trajan's death, though a Trajanic coin found on site keeps the exact date genuinely debated.
What happened here
The wheel turns all day and the miller's household lives to its noise. Water is brought in along a channel, dropped onto the wheel from above where the fall allows, and the gearing turns a horizontal drive into a vertical one for the millstones. One mill can grind for a small town. Where the flow is strong, mills are stacked in a cascade, each using the water the one above has finished with, and a site like that can feed a city. Grain arrives by cart and leaves as flour, with the miller taking a share rather than a fee. Stones are dressed regularly, and a mill also saws stone and works trip-hammers. Floods, drought and the millpond silting are the recurring troubles.
Sources
Roman Maps shows the empire frozen at 11 August 117 CE, the day Trajan died — its moment of greatest territorial extent. Explore the full map →