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Construction of the Julia, Virgo, and Alsietina Aqueducts

by Al Schlaf

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• Part One: Centralized Office for Water Supply

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[Aqueducts of Rome Under Augustus: Part II]

As I had indicated in Part One, this article will deal with the Marcia, Tepula, Julia, Virgo and Alsietina aqueducts, in part due to the fact that the first three are often associated with each other.

Illustration 1

Of the several places Agrippa restored the Marcia, the Ponte Lupo, just upstream from the inverted siphon mentioned in Part One, is the most interesting.^[1] The original structure, as seen in Illustration 1 (left), consisted of two stone arches over the Acqua Rossa, a lower arch dug into the bank and higher arches on the other end, plus a heavy superstructure for the channel. The only parts of this still discernable are the two great arches over the stream. Agrippa reworked it in 34 B.C.^[2], but in a rather less than thorough manner. The two stone arches were left alone, but he added heavy concrete substructions to the arch on the high bank and built a series of new arches on the lower side, buttressing both sides. The superstructure for the channel was five meters high. This was framed, top and bottom, with a projecting course of tufa slabs, approximately fifteen centimeters in thickness. The whole work was done in the era's coarse concrete faced with an inferior reticulate, the buttresses being done in small, rectangular blocks. The concrete itself was of a large tufa aggregate, typical of early Augustan concrete^[3], and laid in uneven courses using a loose, friable mortar. The reticulate is of a crude-cut type of varying size and far below the quality of the example seen in Part One for the Anio Vetus. The tufa for the buttresses is of varying size, roughly shaped and with fairly consistant joints. The Agrippan arch facings are of a better quality. They are of well cut tufa voussoirs, slightly wedge shaped at the back for better bonding. They are laid in long and short pieces to break joint. The mortar joints are very fine and consistant.

Illustration 2

Augustus undertook the second renovation of the era in the period of 11-4 B.C. Due to the narrowness of the structure, he added reinforcing walls of up to ninety centimeters thickness to either side and added three small buttresses to the channel, which are visible over the stone piers of the arches, as can be seen in Illustration 1. The concrete was the same as Agrippa's, but the reticulate was smaller, more regular in dimensions and with closer joints.

In his later restorations, Augustus brought the Marcia into the city on his arch, now known as the Porta Tiburtina, in the year of his twelfth consulate, i.e., sometime between June 27, 5 B.C. and June 26, 4 B.C., as is recorded on his arch. ^[4] I show several illustrations of this notable structure. Illustration 2 (above) shows it as it appeared in 1903. Illustration 3 and Illustration 4 (below) are photos I took in 1973. The arch, as well as the channels above it, is of travertine. To the right of the arch of Augustus is one of the old aqueduct arches, supporting the original channel of the Marcia. This was given ornamental cornices of travertine, to "co-ordinate" with the new structure, on the springline of the new arch. the channel itself was given some ornamentation by means of simple peperino mouldings.^[5]

Illustration 3

Illustration 4

The multiple channels of the Augustan arch are one example of the job the Marcia did in carrying the new aqueduct of Agrippa, the Julia, along with the Tepula, which had become not much more than a branch of the Julia. The Tepula originally had its source intake at the tenth milestone from Rome, along and two miles west of the Via Latina, on the property of Lucullus.^[6] the source was several small rivlets, now identified as the Sorgente Preziosa.^[7] When Agrippa built the Julia in 33 B.C., he carried out radical changes on the Tepula. As the name indicates, the water of the Tepula was rather warm and regarded as unpalatable. Modern temperature readings give the temperature of the water at the source as 63° F, which is probably not too far from that of the ancient temperature.^[8] Agrippa placed the intake for the Julia about two miles further south, tapping a cooler source, 50° F F, and combined the Tepula with it, abandoning the Tepula's original channel for the rest of the way into the city.^[9] Thus, the combined waters were brought in at a temperature of about 53-54° F.^[10] The Agrippan Tepula flowed as one with the Julia as far as the sixth milestone from Rome,^[11] where they entered a settling tank and re-emerged as two separate channels, the Julia on top. This can be seen in the three previous illustrations, where, reading from the top, you have the Julia, Tepula and Marcia.

Illustration 5

Illustration 6

Illustration 7

Illustration 5 and Illustration 6 are of the same site, just to the north of the Porta Maggiore. The black and white one is from about 1899 and the color is mine from the summer of 1973. While it does not show too well in the older photo, Herschel labels the aqueducts in this photo from his book. You can see the open channels, again from the top, of the Julia, Tepula and Marcia. Also labeled are the crossing channels of the later aqueducts of the Anio Novus, Claudia and Felice. At the ground level, running left to right is the Anio Vetus. In the 1973 photo, it can be seen that a tramline has been cut right through the Anio Vetus, Anio Novus and Claudia. Such is progress. At any rate, this is a good example of the relative elevations of the various aqueducts. There is one section of the remains of the Tepula-Julia where they still ran together before splitting into two channels again in Illustration 7 (left) just east of Roma Vecchia.^[12] The channel is of gray, coarse concrete of large aggregate and laid with no order. The tufa reticulate is crude, measuring up to seven centimeters. The blocks are unevenly set with medium wide joints. Below the reticulate are low cut stone blocks, laid in an uneven course.

Illustration 8

Agrippa brought the Virgo into the city in 19 ^[13] for his baths on the Campus Martius, near the Pantheon. The name has three possible derivations. Frontinus reports it was so named after an incident where a young girl (virgo) showed some soldiers, who were hunting for water, the springs where the aqueduct later started. He goes on to state that a small temple was erected on the site with a painting of the event on the inside.^[14] Today, the scene is depicted on the Trevi fountain, itself not far from the ancient terminus of the Virgo and currently fed by the modern Acqua Vergine. Pliny^[15] relates a different version. He states that since the source was near the rivus Herculaneus, it got its name from "fleeing" from the rivus. More probably, it is so named in honor of the Vestal Virgins, who were in charge of sacred water as well as fire.^[16] There are very few remains of the Virgo from the Augustan era. The one important one that I have been able to find, I show as Illustration 8 (above). It was found during excavations in the courtyard of the Palazzo Sciarra in 1887 and 1911. The remains are of four arches, constructed of very well cut blocks of peperino. The keystones of the arches are of travertine as are the string moulds running along the base of the channel. the arches originally stood at a height of seven meters and are 3.15 meters in span.^[17] Further remains of this period, if they exist, will be hard to find, as the Virgo was the second lowest in level of all Rome's aqueducts and ran mostly underground.^[18]

Illustration 9

The final aqueduct built in this era is the Alsietina. It was built in 2 B.C. by Augustus, mainly for his Naumachia, or naval battle arena.^[19] Both the Naumachia as well as the Temple of Mars Ultor had their inaugurations in 2 B.C. Ovid mentions the opening battle (albeit in a less than historical fashion), as a re-enactment of Salamis.^[20] Augustus, in his Res Gestae, states that thirty triremes and quadremes as well as three thousand men in addition to the rowers. The occasion was on the eve of the Parthian expedition and an East vs. West battle in the Naumachia could not have had more propaganda value.

The source of the Alsietina was Lake Alsietinus (hence the name), about twenty miles NW of Rome and near Lake Bracciano. Most of the channel was underground and the only remains we have of it are in the city, near the possible site of the Naumachia, close by the present church of S. Cosimato^[21] Illustration 9 (above). The remains are only 1.5 meters in length and compromise only the sidewalls and floor. The roof appears to have been vaulted. The walls were laid right upon the earthen walls of the trench and composed of a poor, coarse grade of concrete. It is laid with no order and the aggregate varies in size from large to medium Monteverde tufa. The quantity of the aggregate in the mass of the concrete is insufficient for the need, mostly to the top. The reticulate is of the same Monteverde tufa, set with a very friable mortar, composed of a pozzolana of a very poor grade. All in all, it appears to be a "hurry-up job," with little regard for quality. Given the fact that it was for the supply of the Naumachia, and not consumption, this is somewhat understandable.

Under Augustus, Rome had its possibly greatest building projects. This is especially true regarding the aqueducts, as four were restored and three new ones built. Further studies may reveal more sections of this era and enable a better understanding of the whole system.

Back to Part One

Footnotes
1. Esther Boise Van Deman, The Building of the Roman Aqueducts, pp.95-98; Thomas Ashby, The Aqueducts of Ancient Rome, pp. 118-121.
2. Dio, 49. 42. 2. All dates are BC unless otherwise noted.
3. Van Deman, p. 10.
4. Ahsby, p. 89; CIL VI. 1244.
5. Van Deman, pp. 119-120.
6. Sextus Julius Frontinus, De Aquis Urbis Romae, 8. see Online text: LacusCurtius • Frontinus on the Water Supply of Rome
7. Ashby, p. 159; Van Deman, p. 149.
8. Clemens Herschel, Frontinus and the Water Supply of the City of Rome, p. 164; Ashby, p. 160; Van Deman, p. 149.
9. Frontinus, 9; Van Deman, pp. 147-148; Ashby, pp. 159-160.
10. Herschel, p. 164. The question of temperatures may seem trivial, but it is of some importance for consumption, even if it may be more psychological than anything else. As everyone knows, water may be cold to the touch, but not to the palate. For example, a test of the tap water where I live comes up with a temperature of 62-63° F, whereas the water jug kept in my refrigerator is at 38-39° F. This is a marked difference in satisfaction on a hot day. The same tap water temperature is very cold to the touch in the shower, though.
11. Van Deman, p.149.
12. Van Deman, p. 160.
13. Frontinus, 10.
14. Frontinus, 10.
15. Natural History, XXXI, 42.
16. Van Deman, p. 167. One of the Vestal's duties was to daily draw their water supply from the spring of Camenae and Egeria (two obscure water deities) at the Porta Capena. The fact that the water office was right next to the Aedes Vestae and the Atrium Vestae, as well as the fountain of Juturna, may be of some importance here. Also, such a gesture would be in line with Augustus' re-emphasis of old religious values.
17. Van Deman, p. 175; Ashby, p.177.
18. Frontinus, 18.
19. Ibid., 11. Surplus water was also let out for irrigation and for drinking, the latter only in emergency situations and under protest.
20. Ars Amatoria, I, 171-173.
21. Van Deman, pp. 181-185; Ashby, p. 188.

Photo Credits
Author: 3, 4, and 6.
Herschel: 5.
Van Deman: 1, 2, 7, 8, 9.

Al Schlaf earned a degree in Classical Languages and History at The Florida State University, with post graduate work at Florida State, University of Iowa and Trinity College of Hartford, Conn./Rome, Italy Campus.

He currently teaches in the Des Moines Public School system in Des Moines, IA.

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Roman Monuments and Roman Architecture

N.S. Gill
Ancient / Classical History Guide

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