Cloaca Maxima

Listen for a moment. Under the traffic noise of the riverside road, the Tiber moves past slowly, brown and green, sliding along the high stone embankment. Look down at the wall of that embankment, close to the water. There, low and half in shadow, you may see a dark semicircle of old stone, an arch that seems to lead into the hill itself. That arch is the mouth of the Cloaca Maxima. Its name means, quite simply, the Greatest Sewer. It is one of the oldest working pieces of engineering in the city.

It seems strange to make a pilgrimage to a drain. But this drain is one of the reasons Rome could become Rome at all. To understand why, you need to picture the ground under your feet as it was nearly three thousand years ago. The famous hills were dry and safe. The low valleys between them were not. Streams ran down from the higher ground, and the river flooded often. The land where the Forum later stood was wet, soft and unhealthy for much of the year.

Roman tradition gives the credit for draining this land to the Etruscan kings, the Tarquins. They ruled the young city in the sixth century before Christ. The Etruscans were the powerful people of central Italy before Rome rose, and they were skilled engineers of water. The ancient historian Livy describes the work as huge, and he says the common people were forced to do it as hard labour. We cannot check every detail of those early stories. But the idea is clear... a king who could tame the swamp could build a city.

Here is the first surprise. The earliest Cloaca Maxima was probably not a tunnel at all. Historians and archaeologists generally believe it began as an open channel, a managed stream that carried water across the valley and down to the Tiber. Only later, over many generations, did the Romans cover it with stone vaults and build streets and buildings over the top. So the sewer grew with the city. Each age added a piece, repaired a piece, or rerouted a piece.

That is why the structure is not one single object from one single date. It is more like a long record written in stone and brick. Some sections use large blocks of volcanic stone, cut and fitted without much decoration. Other sections show later Roman brickwork and concrete. Engineers in the Republic and the Empire extended it, widened it, and joined new branches to it. Water from public baths, fountains, latrines and streets all flowed into this one great line.

The Romans themselves were proud of it. Pliny the Elder, a writer of the first century, described the city's sewers with real admiration. He wrote that they had survived floods, earthquakes and the weight of collapsing buildings above them. Pliny also tells a famous story about Agrippa, the close friend and general of the emperor Augustus. According to Pliny, Agrippa had the sewers cleaned and repaired, and then travelled through them in a boat. It was a bold piece of public theatre. A great Roman showing the people the hidden works that kept them healthy.

Now for something that many visitors never hear. The Romans gave their sewer a goddess. In the Forum stood a small shrine to Venus Cloacina, a combination of the goddess of love with the spirit of the great drain. The name Cloacina comes from the same root as cloaca. Some ancient writers linked the shrine to stories about the purification of the city. To a Roman, keeping water moving and the city clean was not only a practical matter. It was also a sacred one.

The main route of the Cloaca Maxima runs from the area of the old Forum, through the low ground called the Velabrum, and then out to the river close to where you are now. This riverside district was the Forum Boarium, the ancient cattle market. It was one of the busiest trading places of early Rome, right beside the river port. Ships, animals, merchants and noise... and below all of it, the water of the city running quietly to the Tiber.

Turn and look at the buildings nearby. Not far from the river stand two small temples from the time of the Republic. One is round, surrounded by columns, and is usually linked to Hercules. The other is rectangular and is generally identified with Portunus, the god of harbours. Across the road is the church of Santa Maria in Cosmedin. Its porch holds the large marble face known as the Mouth of Truth.

That stone face brings a second surprise. Legend has it that a liar who puts a hand inside its mouth will lose that hand. Tourists queue to test the story. But many scholars think the marble disc was not made for justice at all. One popular theory says it was once a drain cover, or perhaps part of a fountain. If that is true, the most photographed face in this district may belong to the same world of water and drainage as the sewer itself.

Remarkably, parts of the Cloaca Maxima still carry water today. Modern Rome has its own sewer network, and much of the ancient line has been altered or connected to newer systems. But the old channel has not simply been abandoned. Over two thousand years after the Tarquins, water still moves through stonework laid by Roman hands. Very few structures anywhere in the world have done the same job for so long.

The inside of the sewer is not a normal visitor site. Access to the interior is rare, and it is usually only possible by special arrangement for researchers or small guided groups. For most people, the experience is what you have now: the view of the outlet in the river wall, and the knowledge of what runs under the streets. In the Forum, some openings and sections of the ancient drain are also visible. They are easy to walk past without noticing.

Before you leave, look once more at that dark arch above the water. Think of the long line of stone behind it, running back under the road, under the churches and temples, under the ruins of the Forum. The emperors and their monuments are the famous part of Rome. This is the quiet part. As you walk on, notice the drains in the pavement and the gentle slope of the streets toward the river. The old city is still organising its water, just as it did when Rome was young.