06/11/2015 04:15 pm ET Updated Dec 06, 2017

Provence's Pont du Gard and the Greatness of Ancient Rome

Throughout the ancient world, aqueducts were like flags of stone that heralded the greatness of Rome. A visit to the Pont du Gard (the most famous and impressive surviving Roman aqueduct, near Avignon) shows how these structures still proclaim the wonders of that age. This impressively preserved Roman aqueduct was built in about 19 B.C. The Pont du Gard is actually a bridge over the Gardon River -- the most scenic surviving link of that 30-mile structure supporting a small canal which, by dropping one inch for every 100 yards, supplied nine million gallons of water per day (about 100 gallons per second) to Nîmes, one of ancient Europe's largest cities. Though most of the aqueduct is on or below the ground, at Pont du Gard it spans a canyon on a massive bridge -- one of the most remarkable surviving Roman ruins anywhere.

In July and August, there are six tours a day through the water channel at the top of the Pont du Gard (€4, pay the guide directly, tour is in French and English and takes 30 minutes -- 10 minutes intro and 20 minutes hiking with commentary, generally starts at the bottom of the hour from 10:30 -- times are posted at the museum and entry, be sure to check). There are no reservations; just wait at the metal gate on top of the bridge, on the side opposite the museum. The first 33 people get in. If you do this tour, notice the massive calcium buildup lining the channel from over 400 years of flowing water.

I love to cap my Pont du Gard visit in the city of Nîmes, where you can see the castellum: a modest-looking water distribution tank that was the grand finale of the 30-mile-long aqueduct. The water needs of Roman Nîmes grew beyond the capacity of its local springs. Imagine the jubilation on the day (in A.D. 50) that this system was finally operational. Suddenly, the town had an abundance of water -- for basic needs, as well as for cool extras like public fountains. You can see a little social compassion designed into the water-distribution holes. The lower channel served top-priority needs, providing water via stone and lead pipes to the public wells that graced neighborhood squares. The higher holes -- which got wet only when the supply was plentiful -- routed water to the homes of the wealthy, to public baths, and to nonessential fountains.

Also, in my Travelers Café, Cameron reports on the glitzy Expo Milano 2015 world's fair.