The Aqueducts of Ancient Rome: A deeper look at the Aqua Claudia/Anio Novus and Aqua Virgo

Pliny the elder once wisely wrote, “If we only take into consideration the abundant supply of water to the public, for baths, ponds, canals, household purposes, gardens, places in the suburbs, and country houses; and then reflect upon the distances that are traversed, the arches that have been constructed, the mountains that have been pierced, the valleys that have been leveled, we must of necessity admit that there is nothing to be found more worthy of our admiration throughout the whole universe” [1]. And I have to agree. In Rome, I spent a lot of time admiring the greatness of the Roman aqueducts, three of which were the Aqua Virgo, Aqua Claudia, and the Anio Novus.

There were 11 ancient Roman aqueducts that helped serve and elevate the Roman Empire. These aqueducts helped cement the idea that the Roman Empire really was far more “great” than the civilizations that surrounded it. Emperors often used grand and expensive construction projects to prove the Empires’ (and the Emperors’) true greatness, as well as keep their subordinates happy and uninspired to rebel. 

Although there were 11 aqueducts and all were grand, there were two main aqueduct branches that I found very interesting for different reasons. The Aqua Claudia and Anio Novus brought their water from some of the longest distances for an aqueduct. They were joined together, and provided a large spread area of Rome with water for diverse purposes. The Aqua Claudia moved its water from a much shorter distance and served more of a definite purpose.  Being able to interact with these aqueducts today, and visualize how they served their communities in Ancient Rome was truly something special. The Aqua Claudia, Anio Novus, and Aqua Virgo are all great, yet I found that they were very different.

In the city of Rome, I did as every tourist does: I visited the Trevi Fountain, Piazza Navona, the Pantheon, Campo de’ Fiori, etc. When I was first visiting these iconic places, I didn’t know that some of their most iconic attractions and fountains were supplied with their iconic water from the Aqua Virgo.

Our walk in Parco Degli Acquedotti was a long and hot one. Yet I seemed to forget all about the humid air and infiltrating sun once we were in view of the Aqua Claudia, Anio Novus, and Aqua Felix. It was remarkable to think that the Aqua Claudia and Anio Novus are ancient, built using ancient tools, materials, and resources. As I peered around to the side of the Aqua Claudia and Anio Novus branch, I could see inside the intact Aqua Claudia channel. I thought to myself, “I wonder if it’s possible to walk around in there today”. This question was quickly answered own once I saw the fencing inside the channel. Little did I know that I would be able to experience going inside of this Aqua Claudia channel with our group, along with Roma Sotterranea, when in Vicovaro. We saw the notch marks inside of the channel, which was a truly humbling experience. I was in awe of the minds and hands that were able to build this ancient structure and have it last so well that I could walk through it today. These three aqueducts left the greatest impression on me, and not just because of their greatness. The aqueducts were built on slightly on opposite sides of the ancient building spectrum, with the Aqua Virgo being built in 19 BC and the Aqua Claudia and Anio Novus being built in 52 AD. I had very different experiences with these aqueducts, as they serve very different functions today. I want to explore these aqueducts while also drawing some comparisons.

About the Aqueducts

The Aqua Virgo is the only ancient aqueduct that is still in use today. In 22 BC, the sixth Roman aqueduct was paid for and ordered by Marcus Agrippa, and the ribbon was officially cut on June 9th, 19 BC [3]. The Aqua Virgo was the only aqueduct to enter into Rome from the north. 

The aqueduct had a flow of 41 ft3/s, which is much smaller than the Claudia and Anio Novus. It also was only 13 miles long, while the Claudia and Anio Novus were 43 and 54 miles long respectively. The aqueduct was enclosed underground, until it emerged from the Pincian Hill.  The Aqua Virgo was mainly underground with only 0.7 miles of arches, while the Claudia and Anio Novus had 9 and 7 miles of arches when reaching into the city. 

Both the Aqua Claudia/Anio Novus and the Aqua Virgo used extremely similar construction methods. In 1886, it was reported that pieces of the wall were faced with reticulate (opus reticulatum), which uses tufa and concrete. So the Aqua Claudia/Anio Novus used tufa for the arcades which is what the Aqua Virgo likely used as well. The Anio Novus used brick and mortar while the Aqua Virgo used concrete as well, and then after some restorations used travertine. “The best preserved section of arches can be seen in the cortile of No. 14 Via del Nazareno where there is a series of three travertine arches belonging to a Claudian reconstruction” [3]. 

It’s interesting that while this quote is from over forty years ago, it is still exactly where I was able to see the preserved set of arches from the Aqua Virgo seen above. Forty years is just the blink of an eye when investigating the ancient Roman aqueducts. 

[2]

While the Aqua Anio Novus and Aqua Claudia took in water from the Valley of The Anio mountain range roughly 38 miles East, Aqua Virgo got its water from the Salone Springs which are roughly 8 miles East of Ancient Rome. 

This table shows all 7 Roman hills as well as their elevation. It is comparing the distribution of the Aqua Claudia/Anio Novus and the Aqua Virgo in terms of if they were able to serve the hills. 

Hill Name	Top Hill Elevation (m) [12]	Aqua Claudia/Anio Novus [8]	Aqua Virgo [3]
Palantine	52	✓	x
Capitoline	49	✓	x
Quirinal	64	✓	x
Viminal	76	✓	x
Esquiline	38	✓	x
Caelian	55	✓	x
Aventine	47	✓	x

The Aqua Claudia and Anio Novus’s mixed cistern was located on the Esquiline Hill, and was connected to all 14 regions of Rome with a pipe distribution system [5]. Therefore, it was able to reach all 7 hills of Rome, and had a significant impact on all of ancient Rome. 

Although Aqua Virgo did not serve any of the 7 ancient Rome hills, it did serve the Pincian Hill. Pincian Hill was outside the original boundaries of ancient Rome, just north of the Quirinal Hill, and overlooked the Campus Martius. It laid between the walls later built by Aurelian between 270 and 273. It also reached across the river (modern day Trastevere) [3]. The Aqua Virgo was the third lowest aqueduct, and therefore was not able to have the reach that the Aqua Claudia and Anio Novus did [3]. The Aqua Virgo came into the city eith the height of its terminus at 65 feet.

The Anio Novus is stacked on top of the Aqua Claudia when entering the city of Rome. The Anio Novus and Aqua Claudia were both started in 38 AD by emperor Caligula, and finished in 52 AD by emperor Claudius (although the Aqua Claudia likely was already being used by 47 AD) [7]. 

The Aqua Claudia and Anio Novus drew water from the Anio mountain range. The Aqua Claudia (8th Roman aqueduct) collected water from two springs, the Curzia and the Cerulee [8], which were very high quality water sources at the time. The Aqua Claudia was 43 miles long, with 9 of these miles consisting of arches (arcades).  The Anio Novus (Rome’s 9th aqueduct), collected water from the upper valley of the Anio River which was a marginal water source, until it was moved to an upstream dam [5. The Anio Novus was one of the longest Roman aqueducts of its time, at 54 miles long, with 7 miles of arches. The Aqua Claudia brought in 76 ft3/s of water, and the Anio Novus brought in 78 ft3/s for a combined flow of about 154 ft3/s [6]. 7 miles outside the city of Rome, the Anio Novus was joined in on top of the Aqua Claudia, reaching into the city together on their shared Arches [7]. Bringing together the Aqua Claudia and Anio Novus was innovative and unprecedented at the time. With shared arches, they could greatly reduce construction costs and time. “The cost of 350 million sesterces was approximately half the annual imperial expenditure” [5]. 

The Anio Novus and Aqua Claudia shared a terminus (Castellum) on the Esquiline Hill. The Aqua Claudia came into the city at 220 ft, while the Anio Novus came in at 230 ft.

This photo, also taken in the aqueduct park, shows some of the construction materials used when making these aqueducts. The Anio Novus (on top) is made of Tufa, brick, and pozzolan concrete. The Aqua Claudia is made from precisely cut and balanced Tufa. This photo isn’t completely accurate (see the brick used in one of the arcades), this is because of recent restorations to keep the historical aqueduct upright. 

While the outside of the Aqua Claudia was just Tufa, the inside had a little more complexity. 

Here is a photo from inside Aqua Claudia, where the inner walls contain a type of waterproofing concrete, Opus Signinum. There also is a lot of build up on the walls from the water minerals rushing through, and lines that signify the height of the water. 

Why?

Aqua Claudia/Anio Novus

Caligula has a reputation for being perhaps the most “mad and cruel” emperor but seemed to understand, regardless of his moral intentions, that aqueducts were a positive addition to the Empire. It was common for emperors to show off their personal greatness as well as the greatness of the Roman Empire through their grand construction projects. The Aqua Claudia and Anio Novus were no doubt very grand.

In addition to showing off the grandeur of Rome, the Aqua Claudia and Anio Novus supplied an abundance of water to the people of Rome. The purpose of the Anio Novus and Aqua Claudia seems to be more diverse than most aqueducts, including the Aqua Virgo. About 25% of the water was used for imperial buildings and property, about 45% was for private usage, and the other ~30% was used for the public. The Anio Novus had such a large combined inflow of water that it nearly doubled the total water supply of Rome [11].

Aqua Virgo 

Only about 15% of the water supplied from the Aqua Virgo was for private use, while about 22% of the water was used for buildings in the Campus Martius and Trastevere, and the rest ~63% was used for public use. A lot more of the water from the Aqua Virgo was used for the public compared to Aqua Claudia/Anio Novus [11]. 

It’s a common misconception that the sole purpose of the Aqua Virgo was to serve the baths of Agrippa, however it’s much more likely that a large reason why the aqueduct was built was to supply water to the areas of Rome that didn’t have adequate access to clean water.  “It should be noticed that the Virgo supplied regions VII, IX, and XIV, and thus perfectly complemented the Aqua Julia which Agrippa built in 33 BC”. The baths of Agrippa were actually in use in 25 BC, years before the Aqua Virgo was being used (22 BC) [3]. VII, IX, and XIV being Via Lata, Campus Martius, and Trastevere respectively. Where the baths of Agrippa once were, now the aqueduct supplies the Trevi fountain, some of the Navona square fountains (Fontana del Moro, seen below), the fountain in front of the Pantheon (Obelisco del Pantheon), la Terrina (the “soupbowl”) in Campo De Fiori, the fountain in front of the Spanish Steps (Fontana della Barcaccia), and more. 

The Aqua Virgo is the only aqueduct out of the eleven ancient aqueducts that was still running in the mid 16th century. The reason why the aqueduct was still working, and is still in use today, is because of the restorations. These restorations and general maintenance are necessary to clean out the calcium build up in the channels as well as generally keep up the integrity of the structure.

General timeline of restorations and renovations done on the Aqua Virgo [11]:

Final Thoughts

The Aqua Claudia and Anio Novus were incredibly effective at providing lots of water to a large region of ancient Rome. They came in at 230 and 240 ft, while the Aqua Virgo only came in at 65 ft. The Aqua Virgo was built on the much earlier side of the spectrum (19 BC) while the Aqua Claudia/Anio Novus were built later (52 AD) which supports the trend that the “newer” aqueducts were built in higher. The water from the Anio Novus/ Aqua Claudia channels reached all 14 regions of Rome and all 7 hills, while the Aqua Virgo was not able to reach any of the hills. The introduction of the Anio Novus and Aqua Claudia pathway nearly doubled all of the water supply in Rome. Caligula, regardless of infamous cruelty, knew how important these aqueducts would be to the city of Rome and her glory. 

One of the reasons why the Aqua Virgo was built by Agrippa, was to supply the baths of Agrippa and provide drinking water to places in need. The water did indeed supply the baths as well as the people. Aqua Virgo is the only aqueduct that has been in operation from the time it was built until the present day. The Aqua Virgo, although in continuous operation since its opening, has changed from its initial intent. Originally, it was used to supply water to Campus Martius and complement Aqua Julia’s route by filling in its missing pieces. Trastevere was already being supplied water by Aqua Appia, Anio Vetus and Marci, but it was limited. The Aqua Virgo helped supply this growing area. Aqua Virgo was very effective at providing clean drinking water for people in the areas that needed it, as well as providing water for the baths of Agrippa and Campus Martius in general. Of course, the ancient aqueduct system can’t be fully operational from 19 BC through today, without some work. Many restorations allowed the aqueduct to receive the same original spring water from the Salone area, and was renamed the Acqua Vergine. The aqueduct then began feeding the Trevi fountain, until today.

As Pliny the Elder alluded to, the aqueducts are one of the most incredible feats in the universe. Emporers knew that having such an effective and beautiful connection with water would be important not only for survival, but status. There were 11 different ancient aqueducts, with different sources, lengths, materials, purposes, etc. The Aqua Virgo was the 6th Roman aqueduct, and the Aqua Claudia and Anio Novus were 8th and 9th. With only one aqueduct separating the two, it’s interesting that they differ so much. The Aqua Claudia, although older, is the one that is still standing today (with lots of changes). I find it really interesting that it was so important for emperors for everyone to have access to clean water, especially when thinking about the context of today. In some of the Roman Castellum, for example Pompeii, they had different levels of distribution for different outlets. The lowest distribution point was for the public fountains, middle for public baths and theaters, and the highest for private houses. This meant that when the water level was lower, the private houses’ water was cut, then the baths and theaters, and if it somehow went even lower, finally the public fountains. The main priority was the health and happiness of the people. Although the emperors may have anticipated how bad it would appear if the rich had water while everyone else didn’t, and the intentions may not have been completely pure, the everyday folk got the water. Nowadays, the first to suffer when we run out of clean or plentiful water, are the low income communities. Is there a reason why emperors were able to recognize the issues with this, and we struggle today? 

Spending time with the Aqueducts was quite a humbling experience. Seeing the notch marks and water lines inside of the Aqua Claudia with Roma Sotterranea is something that is difficult to articulate. I just knew that this was something that I wanted to learn more about. The ancient Romans are so impressive and these aqueducts are such a clear representation of that. Although the aqueducts have their many differences, they share the same incredibility.

Citations: 

[1] Deming, David. “The Aqueducts and Water Supply of Ancient Rome.” Groundwater, vol. 58, no. 1, 2019, pp. 152–161., https://doi.org/10.1111/gwat.12958. 

[2] Interactive graphic: The aqueducts of Rome. http://graphics.latimes.com/storyboard-la-fg-roman-aqueducts-g/

[3] Lloyd, R. B. (1979). The Aqua Virgo, Euripus and Pons Agrippae. American Journal of Archaeology, 83(2), 193–204. https://doi.org/10.2307/504901

[4] Le, Nancy. Aqua Claudia and Anio Novus in Parco Degli Acquedotti. [Used for main featured title photo] [5] Motta, D., et al. “Hydraulic Evaluation of the Design and Operation of Ancient Rome’s Anio Novus Aqueduct.” Archaeometry, vol. 59, no. 6, 2017, pp. 1150–1174., https://doi.org/10.1111/arcm.12303. 

[6] Muench, Steve. “Water.” CEE 409/509 Engineering Rome UW Study Abroad Exploration Seminar. 

[7] Parco Degli Acquedotti, 16 Apr. 2021, https://www.parcodegliacquedotti.it/. 

[8] Platner, Samuel Ball. “P28  Aqua Virgo.” Revised by Thomas Ashby, LacusCurtius • Aqua Virgo (Platner & Ashby, 1929), http://penelope.uchicago.edu/Thayer/E/Gazetteer/Places/Europe/Italy/Lazio/Roma/Rome/_Texts/PLATOP*/Aqua_Virgo.html.

[9] Pollett, Andrea. “Aqua Virgo.” Roman Monographs – Aqueducts · Part III, Page 3 – the Aqua Virgo, the Aqua Traiana and the Aqua Alexandrina, http://roma.andreapollett.com/S3/roma-aq6.htm. 

[10] Rinne, Katherine W. The Waters of Rome: Aqueducts, Fountains, and the Birth of the Baroque City. New Haven and London: Yale University Press, 2010. Print.

[11] Schram, Wilke, et al. “Aqua Anio Novus.” Roman Aqueducts: Rome Aqua Anio Novus (Italy), http://www.romanaqueducts.info/aquasite/romanovus/index.html. 

[12] “The Seven Hills of Rome.” The Seven Hills of Rome – Peakbagger.com, https://www.peakbagger.com/list.aspx?lid=5455.