Another Triestine Wonder: San Giovanni Tunnels of The Theresian Aqueduct Connected At Last

The tunnels of the Theresian aqueduct under San Giovanni, Photocredits Upix Fotografia Ipogea
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by Alessandra Ressa

Considered one of Trieste’s greatest engineering works and partly built over the ancient Roman aqueduct, with its carved stone walls, brick tunnels and astonishing archways running silently for miles in the darkness, the Theresian aqueduct may soon become a popular attraction in town.

The Theresian aqueduct is a web of underground tunnels and canals designed almost two centuries ago by the architects and engineers of Austrian empress Maria Theresa. After more than one hundred years of total neglect and the frequent road and housing construction which caused collapses and floodings along the main arteries of the ancient aqueduct, to the point where the whole manufacture was believed to be lost forever, a handful of passionate speleologists with a taste for urban archeology decided to step in.

One of the entrance stairways to the Theresian aqueduct in San Giovanni, Photocredits Upix Fotografia Ipogea.

Explorations of the San Giovanni section of the aqueduct, probably the only part of the great manufacture still standing,  began in the 1980s, but it was only in 2018,  after the discovery of an old metal manhole in a narrow and rugged lane opening into the unmistakably stench local sewer, that the decision to save the important monument was taken. A team of SAS (Società Adriatica di Speleologia) speleologists, led by tireless Marco Restaino, decided to further investigate the intricate underground maze. These brave volunteers soon realized that the sewer was intersected by a much older, narrower tunnel filled halfway up with flowing clear water, coming from one of the many underground streams of Trieste.

The point where the San Giovanni Sewer intersects the acqueduct. Hundreds of buckets filled with rock and debris had to be carried out throgh this long, narrow and very long passage.  

The explorers had no doubts. The narrow tunnel was part of the ancient aqueduct. They decided to wade its dark waters and follow it. They suspected that it was connected to another, longer section, badly obstructed by collapses and cement spills. And it was.

The manhole to the aqueduct  

Four years of hard work followed, slowed down by the Covid-19 pandemic. Most of the obstruction, cement spills, rock collapses and other obstacles, which had caused the ancient tunnels to flood from top to bottom, had to be removed.

Like ants, the volunteers worked in the demolition of the spilled cement barriers, which stood like impenetrable walls in the midst of the passages. The darkness, the water they were constantly standing in, the humidity, the very low ceilings (often less than a meter high), and the need to quickly and systematically remove the heavy, abundant and incessantly piling up debris before it filled the very limited amount of space for movement, did not deter the volunteers.  

One of the speleologists of SAS smiles from one of the narrow passages you can only walk on bent legs.

Week after week, month after month, chain-gang style, hundreds of buckets were carried in and out of the tunnels, often pushed forward while crawling on all fours. With great determination, mountains of rocks and debris were tirelessly removed.  

When asked if I wanted to join in the quest, I could not wait. However, I also could not foresee what was coming ahead. My hopes to exclusively visit the site and take some pictures soon vanished when just a few minutes after I went into the manhole and down the old ladder (not without wrinkling my nose at the initial smell and gooey stuff that stuck to my rain boots) and was asked to push a stack of empty buckets through a passage as large as my hips and half filled with water.

Push it forward, into the unknown… And not enough space to turn around and flee. Forget about taking pictures, my car-mechanic overalls were soaked in a matter of seconds, while I found myself rolling the buckets forward with my head (helmet on), while trying to hold on with my hands to the slippery and cold bottom of the canal, trying not to get stuck in the passage and, most of all, trying not to pass out.

I have luckily survived to tell, and, after the initial discomfort and adjusting, I eagerly joined the chain-gang into filling and passing about the endless super-heavy buckets piled everywhere along the tunnels and filled with rocks and debris.

Pushing empty buckets through the water-filled tunnels is no joke. Dragging them filled with rocks with my back bent in two was no fun either.  

So why go through all this trouble? Why would dozens of people spend their spare time every week  volunteering in digging and emptying tunnels under Trieste? At the core of the project to bring new life to the lost aqueduct and make it accessible to all there is a passionate team of Triestini who strongly believe in the potential of the site.

“I used to call it a reasonable folly – Marco Restaino, SAS president, explains – but now, having removed the water from the tunnels and having found the connections to all the passages (it will take at least another six months to clear all rubble and debris), I am very optimistic. There is over a kilometer of accessible, incredibly beautiful and well preserved tunnels, half of which are made of high ceilings and wide enough space to be accessed safely. My dream is to make the site another special attraction of Trieste.”

Photocredits Upix Fotografia Ipogea  

The Theresian aqueduct is yet another Trieste wonder coming to light after much neglect. And if given the proper importance, it may become one of the city’s most intriguing attractions, not only for its indisputable beauty, but also for its historical relevance.

The Austrian empress managed its construction in 1849. Finances came abundant thanks to a not too popular but nevertheless necessary tax on fish, then very abundant in the Adriatic sea. Before that time, Triestini could only get drinking water from a handful of wells. The water was often contaminated by leaking manure from nearby pastures, and outbreaks of diseases such as typhus and cholera were not uncommon.

If that was not enough, while the population kept growing, the economic boom attracting thousands of laborers into the port, drinking water became scarcer and scarcer. Every drought brought further distress to the local population. The aqueduct project aimed at solving the unsanitary situation, by providing clean, fresh, running water from Trieste’s streams through a number of strategically positioned public fountains, many of which still standing today in town, the water no longer gushing out.

One of the “forgotten” fountains of the Theresian aqueduct in via Crispi

While many Italian cities have greatly invested in their underground treasures, which have in turn become popular tourist attractions, the road to glory for the Theresian aqueduct may still be long. Interestingly, Trieste’s sister city Vienna offers amazing tours of its underground old aqueduct and sewer, through tunnels that are incredibly similar in architecture to the ones in Trieste.

The very popular noir movie The Third Man by Carol Reed, filmed in Vienna in 1946 (starring among others the beautiful Istrian-born Alida Valli), was partly shot in the Austrian capital’s underground network,  reaching its climax with the gripping chase for black market kingpin Harry Lime (Orson Welles) through the arched brick tunnels.

Orson Welles chased by the military police through the aqueduct and sewer tunnels of Vienna in the noir masterpiece The Third Man by Carol Reed (Courtesy of London Films and The Museum of The Third Man, Vienna)

“We want to bring the Theresian aqueduct back to its original splendor – says Restaino – it is an underground historical monument which must be preserved. So far, we were able to clear over 600 meters of the old passages, but the plan is to make it accessible for 1,200 meters.”

If this proportionally tiny section of the aqueduct in San Giovanni may come back to life after all, the same cannot be said for the remaining kilometers of the stunning manufacture running under Trieste, which have been systematically destroyed by construction in the name of progress and are now beyond recovery.

Marco Restaino puts on his “work clothes” before entering the manhole to the aqueduct
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Alessandra Ressa
“Born to Italian-Scottish parents, an explosive combination, reason for my restlessness and love for good food, I’ve moved from San Francisco, California to Trieste 20 years ago. I have a degree in Mass Communication from the University of California, Berkeley, and a Master’s degree in International Cooperation from the Scuola Superiore di Studi Universitari in Pisa. In San Francisco I worked for several years as a journalist and press officer before moving to Albania, Bosnia, Kosovo and other war stricken countries with the United Nations. I am a professional journalist and English teacher, I love the outdoors, exploring caves and unusual places, travelling, meeting people, the opera, singing, the scent of the sea and the whistle of the wind. No other city in the world other than Trieste can offer all this.”


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