In dry Mediterranean towns water is a precious resource. So what better way to display your wealth as a city than to have decorative water features and fonts gushing cooling fresh water to public places and private houses. The overflow even cleanses the streets and drains. In 50AD, the Roman city of Nimes had such ambition and the Pont du Guard was one of the many engineering masterpieces that allowed this to happen. Built to carry a 200 million litres every day (that must be a misprint!) of pure water extracted from a spring miles away, it carries a channel large enough to walk through high up across a valley. The museum is very good, and focuses on research done to understand the whole aqueducts design, function, alteration and decline. It doesnt just concentrate on the Pont du Guard, which is a small section of its 50 km route.
The museum explains chemical analysis of the 30cm thick deposits lining the aqueducts walls similar to the lime scale that builds up in your kettle. Over its 500 years use a cross section of this stone charts date, water quality and flow rates over is operating life and links them to events at the time. It fascinated the nerd in me..