These stone steps near Arles, in southern France, are what's left of the Barbegal mills: a Roman water-powered factory built around 120 to 130 AD. An aqueduct brought water to the top of the hill, where it turned a wheel and dropped onto the next one below. Sixteen water wheels in two rows of eight drove sixteen grain mills.

• ✓Sürmelihindi et al., Science Advances (2018)
• ✓Passchier et al., Geoarchaeology (2024)
• ✓Ritti, Grewe & Kessener, JRA 20 (2007)
• ✓Hero of Alexandria, Pneumatica

These stone steps in France aren't a staircase. They're what's left of a Roman factory. We're often told the Romans did it all with muscle. Machine power came with the Industrial Revolution. But around 1,900 years ago, Romans led an aqueduct to the top of this hill. The water turned the top wheel, then dropped onto the next wheel below it. Eight wheels in a row. Two rows. Sixteen mills, grinding grain by water power. And it wasn't a one-off. In Turkey, a Roman tomb shows a water-powered saw cutting stone, driven by a crank and connecting rod. The same linkage would later drive steam engines. And in Roman Egypt, Hero of Alexandria built a steam engine: a ball that spun on its own steam. It was treated as a novelty. Water power. The crank. Even steam. Rome had the pieces of an industrial revolution. And all that's left of this one are these stone steps.