Aqua Traiana

The Aqua Traiana (later rebuilt and named the Acqua Paola) was a 1st-century Roman aqueduct built by Emperor Trajan and inaugurated on 24 June 109 AD. It channelled water from sources around Lake Bracciano, 40 kilometers (25 mi) north-west of Rome, to Rome in ancient Roman times but had fallen into disuse by the 17th century. It fed a number of water mills on the Janiculum, including a sophisticated mill complex revealed by excavations in the 1990s under the present American Academy in Rome. Some of the Janiculum mills were famously put out of action by the Ostrogoths when they cut the aqueduct in 537 during the first siege of Rome. Belisarius restored the supply of grain by using mills floating in the Tiber. The complex of mills bears parallels with a similar complex at Barbegal in southern Gaul.
Original Sources of the Aqueduct.
Both the ancient Aqua Traiana and the modern Acqua Paola were fed by a collection of aquifer sources in the hills around the volcanic basin of Lake Bracciano. The Italian archaeologist Alberto Cassio in his Route of the Ancient Waters, and his successor Rodolfo Lanciani in 1881 in his Commentary on Frontinus list the sources in the following groups, running clockwise around the lake from Bracciano:
The Architect Carlo Fontana had measured and compared the yield of various of these sources on two occasions in the early 1690s, and documented his measurements in his Really Useful Treatise published in 1695.
The most significant and copious source of the Aqua Traiana is pinpointed by Carlo Fea (1832) as close to the Fosso di Fiora in the modern district of Manziana. Fea makes reference to a document written by the architect Luigi Bernini on 25 February 1667 to Pope Alexander VII Chigi.
The Manziana source has never formed part of the modern Aqua Paola, but, in 1667, Alexander VII wanted to add additional water to the Acqua Paola to power his new fountain in St. Peter's Square. Bernini measured the water at this source as supplying 340 "oncie" of water of perfect goodness and lightness. This water was sufficiently copious, according to his calculation, to double the yield of the Acqua Paola. It supplied as much water as all the rest of the sources put together.
However, the Manziana water had, since the 1570s, been diverted to supply the mills and industry of the duke Paolo Giordano Orsini in the nearby dukedom of Bracciano, so neither Pope Paul V in the early 17th century nor Pope Alexander VII three-quarters of a century later was able to purchase this particular source, and it remains to this day independent from the modern aqueduct.
In the same year that Luigi Bernini wrote his report, the Pope died, and the project was shelved, so the modern aqueduct was eventually supplemented with lake water. The addition of the Lake Water makes Acqua Paola water unhealthy to drink, and gives it a bad taste, which gave birth to the Roman saying "as good as the Acqua Paola" when referring to something of bad quality.
The Manziana source was re-identified in early 2009 by two British film-makers, and its identity was confirmed on 24 June 2009, on the exact anniversary of 1900 years after the aqueduct's inauguration by archaeologist Lorenzo Quilici of University of Bologna.
Distribution of Aqua Traiana within Rome.
The inauguration of the Aqueduct was recorded in the Fasti Ostienses on 24 June 109 AD, which stated that the water was "tota urbe salientem" - a pan-urban network of streetside outlets and basins reaching every part of Rome.
How this distribution was achieved is mostly subject to speculation, but the author Rabun Taylor, in his book "Public Needs and Private Pleasures" suggests that the Aqueduct crossed the River Tiber on a high bridge in the area of the modern Ponte Sublicio, and curved around the Aventine before heading north to the Oppio.
The date of inauguration was also significant, being only a few months before the "Naumachia Traiani" on the Vatican Plain and exactly two days after the "Thermae Traiani" on the Oppio.
Dilapidation and revival as Acqua Paola.
Although the Aqua Traiana, along with all the other aqueducts, was cut by the Ostrogoths in 537, it was the only one restored by Belisarius before his departure in 547, along with repairs to the Baths of Trajan in order to supply water to the grain mills. Over the next few centuries it once again fell in to ruin and ceased to function. It was restored a second time around the year 775 by Pope Adrian I as a way of alleviating the need for the Roman people to carry water in casks from the Tiber to supply the fountains at Saint Peter's Basilica. Subsequently, it once again fell into disrepair.
Camillo Borghese, on his accession in 1605 as Pope Paul V, initiated work on rebuilding the Aqua Traiana, supervised from 1609 by Giovanni Fontana. At that time, the Roman suburbs west of the Tiber River, including the Vatican, were suffering from chronic water shortage. The new pope persuaded the Municipality of Rome to pay for the development of an aqueduct to provide a better water supply to that part of the city.
In 1612, the aqueduct was completed. It was initially called the Acqua Sabbatina or Acqua Bracciano, but was renamed Acqua Paola in honour of Paul V.
Not all original Aqua Traiana sources were available to contribute water to the Aqua Paola. The most copious sources at Santa Fiora, for example, had long since been purloined by duke Paolo Giordano Orsini, who had diverted them to power mills and industry in the city of Bracciano.
The fountain at the end of the aqueduct was referred to as "Il Fontanone" - the Big Fountain - because of its size. It was in the form of a free-standing triumphal arch constructed in white marble with granite columns on high socles. Most of the material was pillaged from the Forum of Nerva. Originally, it consisted of three large central arches, separated by columns, and a smaller one on each side. Water gushed into five basins at the base of each arch. The designer was Paul V's usual architect, Flaminio Ponzio. Among the team of sculptors involved was Ippolito Buzzi, who was responsible for the Borghese coat-of-arms, flanked by the Borghese eagle and dragon, and held aloft by putti, it is presumed to Ponzio's design.
Then, in 1690, Pope Alexander VIII commissioned Carlo Fontana, Giovanni's nephew, to enlarge the fountain. Carlo replaced the five small basins with an enormous single one, the Fontana dell'Acqua Paola, which remains to this day. In more recent times, a small garden has been arranged, hidden behind the structure.