Aqua Claudia / Anio Novus crossing at Porta Maggiore
About
Monumental double-arched travertine structure built by Claudius in 52 CE to carry the Aqua Claudia and (stacked above it) the Anio Novus aqueduct channels across the Via Praenestina and Via Labicana as they entered the city; restored under Vespasian and Titus. This arched aqueduct crossing was fully functional in 117 CE, supplying two of Rome's principal aqueducts (it was only incorporated as a city gate, Porta Maggiore, into the Aurelian Walls in the 270s CE, after our snapshot).
What happened here
Water arrives day and night and never stops. The channel runs mostly underground, following a shallow gradient measured out with a levelling instrument over tens of miles, and it goes up on arches only where the ground drops away. Inspection shafts sit at intervals; gangs work the line constantly, cutting out the lime crust that thickens on the walls and narrows the flow. At the town end the water is divided in a distribution tank — public fountains first by law, then baths, then private houses whose owners have paid for a pipe of a fixed and stamped size. Illegal tappings are a permanent scandal. What arrives is not stored but runs continuously, and the overflow flushes the drains.
In ancient writing
- Frontinus, De aquaeductu urbis Romae 13–15
Claudius's two aqueducts, the Aqua Claudia from the Caerulean and Curtian springs and the Anio Novus, brought in on the same arches and finished in 52 CE.
- CIL VI 1256, building inscription 52 CE
Claudius's inscription on the aqueduct crossing itself records that he brought in the Aqua Claudia and the Anio Novus at his own expense; Vespasian's and Titus's repair texts run below it on the same stones.
Sources
Nearby
Roman Maps shows the empire frozen at 11 August 117 CE, the day Trajan died — its moment of greatest territorial extent. Explore the full map →