From a series written for ABC Radio National’s Blueprint for Living. The aqueduct was first broadcast on 15th October 2022. You can listen to the audio here.
Two thousand years ago, the Romans were masters of the aqueduct. Many were dotted throughout their Empire and still stand; some even remain in use. An aqueduct is a sign of a sophisticated civilisation and a demonstration of the ingenuity of builders and engineers as they move water from source to city. One of the best is in Segovia in Spain. In fact, it’s one of the most thrilling structures in the world. In everyday use until comparatively recently, it transported water from the River Frío some fifteen kilometres away, bringing it into holding tanks where any sediment could settle before the clear water flowed onwards to the centre of the settlement. The engineering involved was considerable but its showpiece was the soaring aqueduct that traverses the valley right in the heart of the old city. With two tiers of stone arches, it’s the sort of structure that would become more familiar nearly two thousand years later in the viaducts built for the new railways but even now its sheer scale makes it a mind-boggling sight. What makes this aqueduct especially remarkable is how its giant stone blocks are laid without using mortar, meaning there was nothing that weather could erode except the stone blocks themselves. At over 800 metres long and 28 metres high, it holds a single conduit, the only part that had mortar to ensure there would be no leaks. Lead could have been used but it was known even then that its use in water pipes was hazardous to health.
In nearby France, there’s another remarkable example, the Pont du Gard, which helped carry water from Uzès to the Roman settlement at present-day Nimes, a distance of about 50 kms. The immense structure has three tiers of arches and crosses the Gardon river, which was prone to surging currents during periods of heavy rain, so the Romans streamlined the leading edges of the lower arches to mitigate the potentially destructive impact of the water. The bridge also shows exactly how it was built, with stones jutting from its sides that supported wooden scaffolding that held the arches in place during construction. Again, only the water channel uses mortar but there are some iron pegs that hold the giant sandstone blocks in place, with the whole structure braced against each bank of the river. It’s a surreal sight, standing grand but alone in the surrounding countryside, a complete contrast to Segovia’s, which dwarves the town.
The Roman engineer Frontinus, who built water systems around Rome, called aqueducts ‘the most solemn testimony of the Empire.’ That testimony remained when aqueducts were introduced by later civilisations. Like the Vijayanagara Empire in India with its complex system of aqueducts and reservoirs created in the 1300s to bring water to its capital, Hampi. And the Incas in Peru at the same time, who channelled the meltwater of the Andes to remote settlements like Macchu Picchu, using a precision and ingenuity that still astounds. Despite our constant need for water, we rarely celebrate its passage, although it’s impossible not to be moved by the immense hydro-electric pipes in places like Tasmania and Norway. When this crucial infrastructure is hidden out of sight then we lose a sense of gratitude for water’s importance. And frankly there’s no excuse for an ugly bridge. The ancient aqueducts in Segovia and the south of France remind us that form and function can come together in the most breathtaking way, leaving us with masterful symbols of inspiration and enchantment.