Aqueducts carried water into cities using gravity alone, along channels set at a slope.

The longer version

Water only flows downhill, so engineers aimed at a steady, gentle fall over many kilometres, keeping the channel just high enough to reach the city. They surveyed the route first, then ran the channel as a covered conduit, cutting tunnels through hills and raising arcades across valleys where the ground dropped away.

Settling tanks, inspection shafts, waterproof linings and regular cleaning kept the supply usable, and the constant flow was shared between public fountains, baths, workshops and a few private houses before it drained away. Slight slopes matter: too steep and the flow scours the lining, too shallow and sediment settles.

Where this entry sits

This set looks at ancient civilizations, old inventions, trade routes, calendars, and the ordinary objects people once used every day. Nothing here is advice or opinion, just short notes about how daily life used to be organised long ago. The full list sits on the History page, where every entry is listed in order.