The excerpt below is taken from the book “Rome in Africa” by Susan Raven in the chapter titled “Conquest of a Country”.
“There is a legend that a Roman soldier fell in love with a native (Carthaginian) princess, who as proud as Dido, would have nothing to do with him; she would never marry him, she said, until the waters of Zaghouan flowed to Carthage. This impossible condition was fulfilled, the fifty-mile aqueduct which still strides across the plain of the River Miliana was built; the Roman claimed his bride, who threw herself in despair from the aqueduct’s summit. The story perfectly illustrates that the Roman genius for the art of the possible extended to the improbable. The Romans saw possibilities where none had seen them before. Where others had seen them but had been overwhelmed by difficulty, they saw only a job to be done, and did it.”
Unfortunate that the lady from the story did not have access to the various resources we do in modern times like google. She could have made a more unreasonable request if she had known that building aqueducts for Romans was a walk in the park.
This post is inspired by my recent visit to ‘Les Ferreres Aqueduct’ on the outskirts of the modern city of Tarragona (Tarraco in ancient Roman times). More on Ferreres later in the post.
The Romans certainly did not invent the concept of the aqueduct. Archaeological evidence apparently points to the existence of aqueducts from as far back as the ancient Minoan and Mesopotamian civilisations. Certainly the Greeks and Etruscans also built aqueducts and big city states such as Athens had aqueducts a few kilometres long supplying them with water.
But what the Romans did was to take the concept of the aqueducts, make it their own and then advance it way beyond what had ever been done before. The Romans were great at engineering and also at reverse engineering. Consider the case of Rome and its navy.
Prior to the first Punic war Roman territorial expansion was primarily over land in Italy but then it came into conflict with Carthage over the island of Sicily. Now Carthage was already a great naval power and dominated the Western Mediterranean whereas Rome did not have a decent navy to speak of. So what did the Romans do? They took a Carthaginian quinquereme (a ship with three banks of oars) that had run aground and they reverse engineered it to make their own fleet of quinqueremes. Of course it took many more wars for the Romans to gain experience of managing a navy successfully but once they took to it, they didn’t stop despite multiple disasters.
Similarly for the aqueducts. Whereas earlier Greek aqueducts probably were a few kilometres long, Roman aqueducts stretched for tens of kilometres. Aqua Marcia, one of the 11 aqueducts that supplied Rome with water ran for over 90 kilometres.
What only struck me very recently as I stood staring at a model of the ancient Roman city of Tarragona was that the beautiful arches that we see of the aqueduct today are only a very small part of the aqueduct. The majority of the aqueduct actually runs underground. Yes, in hindsight it seems very obvious.
So how did an aqueduct work in ancient times? Simple answer: gravity.
You had a big water hungry city at point A. Your diligent Roman surveyors have identified a suitable pure source of water at point B which let’s say was 20 kilometres away. Now what the Romans did was to build a long gradually sloping channel system from point B to point A. Of course, the one important consideration in this is the fact that the source of water needed to be more elevated than the city that it was feeding into. So the Romans built this downward sloping channel starting at the source and gently brought it down to the city so the water flowed on its own without needing any pumps. The slope was only a few centimetres every few hundred feet. The spectacular aqueduct of Pont du Gard in France descends a total of 17 metres over 50 km. This translates roughly into over 30cm drop every kilometre. Think about the precision in engineering you need to build such a slightly inclined underground tunnel over such long distances.
When you have to traverse tens of kilometres you are bound to also encounter differences in local terrain. Whenever the Romans encountered a deep gully or valley, you can see the aqueduct breaking out into those beautiful archways that we so admire today. But otherwise the channels ran underground.
Being the superb engineers they were, the Romans also had what were called the siphon aqueducts. In this the water flowed downward in a U shaped channel except that the mouth at the at other end of the U was placed at a lower level than at the beginning so water could continue flowing. However, because of amount of pressure that the pipes built in ancient times could withstand, the Romans preferred building arches.
With almost 1 million residents at the height of its splendour, Rome needed 11 aqueducts to provide it with the water necessary to feed the public fountains, the baths and provide running water to the affluent homes in the town (the last paid for their water supply and numerous records indicate that cheating was rampant- something that goes on even today). Think about how running water in your house was a luxury that did not come to pass for many many more centuries after the collapse of Rome.
The oldest aqueduct in Rome was the Aqua Appia- operational in 312 BCE, commissioned by the same man Appius Claudius Caecus, after whom the Appian way is named. The latter is one of the oldest straight roads in the world, parts of which are still being used. The last aqueduct into Rome was built in the mid 3rd century CE. One of the aqueducts Aqua Virgo, built by Marcus Agrippa, still provides water to some of the fountains in Rome- most notably the Trevi fountain.
It was all fine and dandy to have numerous aqueducts running into town but somebody had to maintain it. These were where teams of hydraulic engineers came in. They must have had their hands full with regular maintenance work (think mineral deposits accumulation, pipe blockage, breakage etc) and any major disruptions. You could almost write a book about the life of an engineer attempting to do his work while he gets embroiled in a lot of intrigue and at the same time a volcano is about to erupt. Sorry folks! This book has already been written. I read Robert Harris’ Pompeii a long time ago- methinks it’s time for a reread.
With the collapse of the Roman Empire many of their engineering secrets were also lost. This led to people in the Middle Ages looking on some of the structures the Romans had erected in wonder and awe and wondered if some supernatural force had been involved. This is reflected in some of the names they gave them for example Les Ferreres aqueduct is called ‘Pont de diable’ or ‘Devil’s bridge’; ‘Los Milagros’ or ‘The miracles’ in Merida, Spain.
Video of the Pont de Diable
Travel anywhere to the territories of the erstwhile Roman empire you will sooner or later come across an aqueduct. Three of the most well known and well preserved aqueducts and by that I mean the arched bits, today include the aqueduct at Segovia, the Pont du Gard at Nimes and Les Ferreres aqueduct near Tarragona. You can also see the remains of many aqueducts around Rome- some along the Appian way, on top of the Porta Maggiore and even adjoining the Palatine hill.
This is a nice quick video that talks about Pont du Gard
And of course as you drive into modern day Tunis, you can still see the remains of the aqueduct that the lovelorn Roman soldier built for his princess 🙂