Aqua Traiana

Roman aqueducts: Rome Aqua Traiana (Italy) Rome - ROMA Aqua Traiana
For the photo's, see below
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As suggested by its name, Trajan built the Traiana. Before its construction, the Trastevere region depended on aqueducts across the river (Aicher, 1995:44). The literature and study of the Aqua Traiana is somewhat limited because it was established after Frontinus. Inscription CIL 6.1260 (See Chapter 3.5 of the thesis XXX), however, does indicate that it was established in AD 109. Further evidence commemorating its establishment is found on a sestertius coin (see photo) dating from the Trajan's fifth consulship and by a lead 'fistulae' found on the Esquiline near the baths of Trajan bearing the markings THERM(ae) TRAIAN(i) and AQ(ua) TR(aiani) (Evans, 1997:131). It is also mentioned in the 'Liber Pontificalis' in the life of Felix II (AD 355-8) and in an inscription which records repairs to it by Belisarius (Ashby, 1935:299). This inscription seems to have been lost since the seventeenth century.

Source and course
Its source was taken from the high-quality springs located near Trevignano, northeast of Lake Bracciano. Its course generally ran south following the high lands of its region. One section of its conduit was discovered in 1912 underneath the American Academy and is still accessible today. Another discovery was made in 1990 and 1991 in the Via Giacomo Medici. Remains of a mill powered by the aqueduct were found at this location. Other evidence suggests that a terminal 'castellum' of the Traiana resided under the present day casino of the Villa Spada. The Traiana's estimated length was 35 to 60 km. A more accurate figure is difficult due to the lack of written sources and material remains.
The height of the aqueduct and its point of entry made it possible for the Traiana to distribute water to all fourteen districts in Rome. The point of entry, above the Transtiber, indicates that its primary role was to service the needs of that district. This area had grown rapidly during the first century and required more water to satisfy the district's needs. The Appia and the Alsietina would have been too low to have fulfilled this requirement.
The necessity of supplying his Baths with water seems to have been met by Trajan with the introduction of the Aqua Traiana. Epigraphical evidence suggests that a certain amount was distributed throughout the city and either supplied the new Baths directly or freed water from other aqueduct lines for that purpose (Anderson, 1985:508).
Recent excavations on the Janiculum have lead to speculations about the use of water mills on the Aqua Traiani. An excavated complex in the region shows that location of water mills, using undershot wheels at the point where the Traiana's gradient starts to increase but before it becomes steep enough to use overshot wheels, looks like an attempt to squeeze in the maximum number of mills possible in this area. The course of the Traiani and Alsietina follow the peculiar configuration of the Janiculum salient traced by the Aurelian Walls at this location (Wilson, 2002:13). Interestingly, Procopius tells us that the line of the Aurelian Walls on the Janiculum was intended to protect the water-mills there.

The Traiani was the last great aqueduct built in Rome. Frontinus' (87.2, 88.1 and 89) praise of Trajan seems well justified when considering Trajan's foresight in building the first aqueduct on the western side of the Tiber, and using it to supply the Eastern side. This was opposite of the usual practice (Evans, 1997:132).

From E.J. Dembskey: The aqueducts of Ancient Rome" (master thesis 2009)

Early 2010 two filmmakers / amateur archaeologists claim to have found the source of the Aqua Traiana, see

The Sette Sale (Seven Halls) cistern

The water supply of Trajan's Baths was stored in a huge cistern - known since the Middle Ages as Sette Sale, the Seven Halls - that was fed by a branch aqueduct that came from the Esquiline hill. Located at the edge of the park, the cistern is well preserved (entrance on the Via delle Terme di Traiano). Since it is oriented differently than the Baths, it was once thought to have belonged to the Domus Aurea. However, the many brick stamps found in its wall prove that the cistern was built at the same time as the Baths.

The cistern is on two levels, each consisting of nine parallel compartments more that 5 meter wide and 30 to 40 meters long (their length differ because of the curve of the eastern perimeter wall). The lower level stands directly on the ground supporting and elevating the upper level - the reservoir proper - which was therefore high enough to ensure that the water could flow out with enough pressure to supply the Baths.

The cistern was partially embedded in the ground, so that the back curved wall and the two side walls are partially covered and buttressed by the embankment, while the straight front wall with alternating rectangular and semicircular niches was in sight. Later alterations made when the cistern was no longer in use, isolated the terrace and eliminated the connecting elements that adjusted for the difference in height between the front and back of the cistern.

Large windows opened in the niches of the upper level provided ventilation. The water flowed out of pipes set in the low-level niches into a large conduit a stretch of which has been found in front of the northeastern exedra of the Baths.
The compartments could hold over eight million liters of water. Their walls and floors are faced with waterproof plaster; they are interconnected by a system of staggered openings that prevent the formation of water currents or stagnation.

The cistern has always been visible over the centuries. In the Middle Ages, one of its compartments was used as a burial area: more than a thousand skeletons were discovered here during the 1967 excavations.

Text of the information panel in front of the cistern (May, 2010)

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Acqua Paola remains

Opus reticulatum

Series op 'repairs'

Less structured
brick work

Ancient and modern

Aqua Traiana pier

piers of 2 aqueducts

Overarched by the Paola


Aqua Traiana alone

Reticulate inside (1)

Channel of the Traiana

Modern sewer-pipe

Plastered ceiling

remains of form work

Reticulate inside (2)

Concave plaster

The end (here)

Excavated mill-stone

Lanciani's plan

Also Aqua Traiana?

Details of masonry

At the Janiculum hill

Fontana Paola

Abundant water supply

J.H. Parker's plan

Possible route

Sette Sale

Traian's sestertius