Aqua Anio Novus

Roman aqueducts: Rome Aqua Anio Novus (Italy) Rome - ROMA Aqua Anio Novus
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The Aqua Anio Novus proved to be the zenith of all ancient Roman aqueducts. Both the physical remains and purpose of these two lines can be argued to be the most ambitious and innovative of the Roman aqueducts. Certainly they are the most visually impressive. Like the Aqua Claudia, the Anio Novus was started by Caligula and completed by Claudius. The steady growth of imperial Rome in the early first century increased the demand for water that was not only used for drinking and washing, but also for luxurious and decorative purposes. Frontinus (2.14) indicates that its muddy source was situated near that of the Marcia and Claudia:
'The Anio Novus has its intake at the forty-second milestone on the Via Sublacensis in Simbruibe territory, from the Anio River, which flows muddy and turbid even without the bad effect of rain, since it has cultivated and such lands around it, and as a result, quite loose banks. For this reason a settling tank was installed away from the intake of the conduit, where the water might settle and be filtered between the river and aqueduct channel. But even so, it comes to the city turbid whenever there are heavy rains'.
Trajan responded to the shortcomings of the source mentioned by Frontinus by moving it upstream to the lake formed when Nero dammed the Anio for his villa )1. According to Frontinus (1.15), it is supplemented by 'the Herculanean Brook, which has its source... opposite the springs of Claudia'.
Aquae Claudia and Anio Novus
at Roma Vecchia
From its source, the channel descended along the river, always on the left bank and generally underground. The aqueduct divided into two channels above Tivoli, one of which followed the traditional hillside course, while the other took a shortcut by turning south and tunnelling deep into the mountain before rejoining the original channel near Gericomo on the slopes above the Campagna. When the Anio Novus surfaced, just after its clearing tank near Capannelle, it travelled on the Claudia's channel into Rome. )2 Its terminus was a large 'castellum' on the Esquiline Hill near the temple to Minerva Medici that the Novus shared with the Claudia (see D.27).
Frontinus indicates that the 'castella' in which the two systems flowed made service possible to the Caelian, Palatine, Aventine and Transtiber. Supplies were first brought to the Palatine through siphons, however, restorations soon allowed for the waters to be carried over an aqueduct bridge. Frontinus alludes to an impressive bridge that permitted distribution to the Aventine. There is, however, no remaining archaeological evidence to confirm the descriptions this. The same is true with the delivery to the Transtiber. Frontinus does not note any arcade in connection with this district, and therefore one must conclude that water travelled here through pipes along the Pons Aemilius. The Anio Novus delivered 190,000 m3 per day. According to an inscription on the Porta Maggiore, the Novus spanned 87 km before Trajan lengthened it to 92 km. It was the highest of the Roman aqueducts.

The relationship between these the Anio Novus and Claudia parallels that of the Tepula and Julia. The waters of the two aqueducts were mixed and then separated as each channel entered the city. Archaeological evidence supports this connection with the findings of various 'castella' and the actual positioning of their respective specus. The two systems did enter Rome separately, and it is worth noting that the Arcus Caelimontani was a crucial branch of the Claudia. This branch line might have been built to supply the Domus Aurea, particularly its extensive waterworks including the 'stagnum' located in the valley of the Colosseum, and the nymphaeum on the Caelian. It might have been used to augment the water supply on the Palatine and in the centre of Rome after the fire of AD 64. Because of this maintenance required by these two aqueducts, water administrators and maintenance crew doubled in numbers. Men were employed to patrol the courses of the lines to dismantle the numerous illegal taps.
Grotte Sconce
Repairs on the Aquae Claudia
and Anio Novus
One interesting, but puzzling, feature of the Anio Novus is the 'castellum', now known as the Grotte Sconce. It is located along the Viottola Pomata on the same side of the road as the Arcinelli bridge, closer to Tivoli by several hundred metres (Aicher, 1995:136). Through the 'castellum' would have served as a settling tank, it had another purpose. This was to divert water to the three aqueducts on the slope below it. A diversion channel descends rapidly from the Novus, and about 75 metres from the 'castellum' a vertical shaft drops water directly into the Claudian channel. A similar technique was used on the Marcia 15 metres further on, and again for the Anio Vetus at the end of the side channel. For what purpose water was diverted from the Novus can only be guessed. One possible reason is that the diversion would allow the channel after the 'castellum' to be worked on without depriving Rome of its water. It would also allow work on the Marcia and Vetus upstream of this point without completely depriving their distribution points of water (The Novus and Claudia used the same 'castellum' in Rome, so this would not apply to the Claudia). Another possibility is that after a storm, when the Vetus ran muddy, the Vetus supply was suspended and water from the Novus was diverted instead.

The Novus has another side channel at Fossa della Noce, which may have also served to divert water to the Marcia below. This may have been a simpler but functionally equivalent system to that at Grotte Sconce, suggesting that this system of water diversion was perhaps fairly common. The reason was probably to divert water while repairs and maintenance was undertaken.
Frontinus' data on the Anio Novus and Claudia point to the differences between them and previous aqueducts. Instead of having a specialised purpose, these systems provided water for a wide variety of uses. Approximately one-fourth of its capacity furnished imperial buildings and property (the palace complex on the Palatine took most of this), roughly 45% of its total volume supplied privati. Less than one-third served usibus publici. The Claudia and the Anio Novus almost doubled the existing total water supply in Rome. The introduction of the two systems took a great deal of time, money and administrative re-engineering, but the result was the increase in water supply for every aspect of its usage.

)1 Very little is known of what must have been a remarkable dam. It is estimated that it was 40 metres high. Little of the remains have been found, perhaps due to the ruggedness of the location. The dam was destroyed in 1305 A.D. by floods (Hodge, 1991:124).
)2 This can be clearly seen in Figure D.28. The construction of the Novus channel has a different look to the older Claudian structure.

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

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11 arches

Overgrown arcade

In need of repair

Inside the construction

North side

Break down


The intrados

Mediaeval tower

Road crossing

Ponte degli Arci

Work of art

Grotte Sconce

Vault of a basin


Drawing of GS

Ponte Arcinelli


Inside Anio Novus

Print of formwork

Undesirable overgrowth

Side branch

Anio Novus

Sinter layers




Double bridge

Inside the channel

Valle Barberini

Vault of the bridge

In the twilight

Ponte San Antonio

Repairs and Decay

Side branch


Villa Sette Bassi

Comparative heights

Plazza di Porta Maggiore

Text on Porta Maggiore

Mediaeval view

Plazza di Porta Maggiore

Castellum Aquae

Ad Spem Veterem

Side branch

Via G. Pepe


Ramus Aquae Juliae

Piazza Vittorio Emanuele

Trophies of Marius

Piazza Vittorio Emanuele

Front, cross-section

View and cross-section