[2]: 271-2 Frontinus describes its source as near that of the Aqua Claudia[5] and "forty-second milestone on the via Sublacensis, in the district of Simbruvium.
The water is taken from the river which, even without the effect of rainstorms, is muddy and discoloured, because it has rich and cultivated fields adjoining it and in consequence loose banks.
To improve the quality of the water Trajan connected additional sources from the two uppermost of the three lakes formed by Nero for the adornment of his villa at Subiaco, thus lengthening the aqueduct to 58 miles and 700 paces.
From its filtering tank near the seventh milestone of the Via Latina, it was carried on the arches of the Aqua Claudia, in a channel immediately superposed on the latter.
Spurs are visible on the various pylons, which were used to hook and support the scaffolding both during the construction of the bridge, but above all during the numerous restorations.
In the post-Severan period it was reinforced by covering it almost completely with brick-clad opus caementicium[10] and adding small arches at the bottom of the bridge.
The Anio Novus bridge, about 85 m long and about 10 m wide, has a few small arches except for the main high and narrow one for the Acqua Nera.