the Aqua Traiana's course (dotted line)

During the reign of emperor Trajan (AD 98-117), despite nine aqueducts were already working, the district on the western side of the Tiber, Trans Tiberim, had been left without a supply of drinkable water. The only aqueduct that reached Rome from the north-west was the Aqua Alsietina, which ran almost entirely underground, except a very short part; having been been built with the main purpose of filling emperor Octavianus Augustus' naval stadium (see Curious and Unusual page 4), the water it drew directly from the small Lacus Alsietinus, now Lake of Martignano, was not suitable for drinking. Trajan sought for clean springs in the same area, finding them by the hills on the western side of the Lacus Sabatinus (now Lake of Bracciano). Minor springs located on the eastern side of the lake were also used, so that the first stretch of the aqueduct followed about half of the lake's perimeter. The Aqua Traiana was completed in AD 109. Trajan bought all the grounds crossed by the aqueduct, so that the tunnel could always run through a protected area 30 feet in width, from the lake all the way down to Rome. Its tunnel was at ground level for most of its course; approaching the city, though, some parts ran above an aqueduct.

The aqueduct entered Rome from the Janiculum, and the final outlet was located at the very top of the hill, one of the city's highest spots, where the Aurelian way approached Trastevere from the west, and where Aurelia Gate was built around 275 (see also Porta San Pancrazio). The steep drop from the top of the hill to Trastevere's plains could also provide hydraulic power to the local mills.

The Aqua Traiana remained functional until 537, when the Goths damaged Rome's aqueducts. During the Middle Ages it was reactivated several times, but it never worked steadily again, until it was completely restored and partially rebuilt in the early 17th century. By that time, along the Aqua Traiana, renamed Acqua Paola, small stone pyramids were set at regular intervals, marking the openings of the tunnel's roof used for maintainance works. What is visible today within the urban area are three parts of the aqueduct, belonging to its last mile before the final outlet. They follow via Aurelia Antica, the modern road corresponding to the ancient roman Aurelian way, still narrow in some parts, and sometimes congested with traffic.

the aqueduct along the Aurelian way

the red lines indicate the visible parts of the aqueduct

the commemorative archway of Paul V

Along the first part, i.e. the one once closer to the final outlet, the aqueduct reaches its maximum height, about 6 metres (or yards), not very tall, compared to other aqueducts. This stretch of the Aqua Traiana marks the boundary of a large public park, Villa Pamphilj; once this was the suburban residence of the Pamphilj family, whose most outstanding member was pope Innocent X (1644-55). Where via Aurelia Antica makes a slight bend, the aqueduct crosses the road thanks to an archway, whose look is clearly not ancient roman. Pope Paul V had it built in 1612, when the Aqua Traiana was restored; in the upper part of the archway, his commemorative plaque and family coat of arms remember his sponsorship.

The text, though, reveals a curious mistake: according to the third line, that reads AB · AVG · CAES · EXTRUCTOS ("built by emperor Augustus"), the pope and his architects wrongly believed that what they had just restored was the Aqua Alsietina, actually built by Octavianus Augustus for his naval stadium, not the Aqua Traiana. The same mistake is also found in the even larger inscription above the huge Fountain of the Aqua Paola (see The Rioni, Trastevere). On the right side of the road (walking westwards), the aqueduct gradually turns lower and lower, until the series of arches disappears quite abruptly.

detail of Paul V's commemorative plaque

Very soon the road goes slightly uphill, then downhill again; immediately past this spot, the aqueduct appears again, on the southern side of the street. Extremely low at first, it grows gradually higher until it acts once again as a boundary wall of Villa Pamphilj; in fact, the main entrance to the park is located below one of the aqueduct's arches.

the third visible part of the aqueduct

The last part of this stretch is barely recognizable, because the brick texture of the aqueduct has been covered with plaster, and appears smooth, as an ordinary wall. Then, by a crossing, the Aqua Traiana comes to an end again. The third part stands about 200 metres or yards further west, by the crossing with via del Casale di San Pio V, next to a block of modern buildings. The aqueduct can be told by the series of arches, whose uppermost part emerges from the ground for about 1 m (3 ft), remaining very low. Here the visible part of the structure is no more than 3-3.5 metres or 10 feet high, and it corresponds to the actual water tunnel, whose average height (inside) was about 2 metres or 6 feet.

On the corner where the aqueduct makes a bend, turning towards the north-west, a surviving pyramid rests above the tunnel's roof. (↑ above) the surviving pyramid, now located by a petrol station (right →) The best way to reach the remains of the Aqua Traiana is to walk from San Pietro station (bus 64, or regional railway FR3) along via delle Fornaci, to the crossing with via Aurelia Antica (but mind the traffic!). Also the bus line 31 stops along via Leone XIII. Other public transport facilities can be reached following via del Casale di San Pio V: from the end of this road, the bus stops of lines 490 and 495 are 300 m or yards ahead, while 500 m or yards ahead is the nearest subway station, Cornelia (line A).

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THE REMAINS OF THE AQUA ALEXANDRINA

the direction of the Aqua Alexandrina: the last part ( o o o ) is hypothetic

The Aqua Alexandrina was the last aqueduct built in ancient Rome, in AD 226, over 500 years after the first one. Its purpose, according to emperor Alexander Severus who was the sponsor, was to carry water to the Baths of Nero, which stood in the western part of the Campus Martis, more or less where today is piazza Sant'Eustachio (see The 22 Rioni, page 8). The new aqueduct drew water from springs located about one mile south of the via Praenestina, east of Rome; its direction was initially almost parallel to the same way, then it made a slight bend towards the south, heading towards the via Labicana (today, via Casilina), and shortly before approaching the city walls it turned into an underground channel, and entered the urban area probably by Porta Praenestina (now Porta Maggiore); from there it likely followed the Esquiline hill, then the Quirinal hill, finally sloping down towards the plains of the Campus Martius.

There are parts of this aqueduct still standing, up to where it crossed via Casilina, in Torpignattara district; the rest of its direction is hypothetic, as nearby (i.e. in via del Mandrione, see page 2a) stood also the Aqua Claudia with the Anius Novus, the triple duct of the Aqua Marcia, Tepula and Iulia, and even the Anius Vetus, although the latter ran below the ground level. The underground tunnel of the Aqua Alexandrina has never been found. None of its urban parts has been left standing, and the same aforesaid course is partially hypothetic because the underground duct has never been found.

Within the urban area, the longest parts of the aqueduct can be seen in the eastern outskirts, whereas beyond the modern city boundary the aqueduct is still fairly preserved for most of its length. The first surviving stretch is located in viale dell'Acquedotto Alessandrino, where an unbroken series of arches crosses a public garden for 250 m (or yards). The structure is not in very good condition, but its overall look is still interesting. Its direction seems to converge towards the aforesaid via del Mandrione. the Aqua Alexandrina in Tor Pignattara district →

(↑ above) the tomb of St.Helen, or Tor Pignattara; (↓ below) a detail of the few pots left in the vault

In via Casilina, not far from the south-eastern end of this part of aqueduct, another interesting and not too famous ancient remain can be seen: the monumental tomb of St.Helen, mother of emperor Constantine the Great, who died in 328 AD. It consists of a round hall built in bricks, with a tall dome (collapsed a long time ago), which stood by the entrance of a Christian underground cemetery, or catacomb, named after the saints Marcellinus and Peter. The inside has eight niches all around the hall; one of them matches the entrance, while the large sarcophagus in which St.Helen's body was buried, made of red porphyry (a marble only used for imperial family members), now kept in the Vatican Museums, stood in the largest niche, opposite the entrance. The central space of the hall is now occupied by a tiny church, Santi Marcellino e Pietro, built in the early 17th century. According to a particular technique in use by the late imperial age, the weight of the dome was reduced by inserting earthenware pots or amphors in the building material; a few of them are still there. This was worth St.Helen's tomb the popular nickname of Tor Pignattara (more or less "pot tower"), which also became the name of the whole district. In ancient times, instead, this site used to be called ad duas lauros ("by the two laurels"), because of two laurel trees planted by the large tomb, a symbol meaning that the building belonged to the imperial family.