Aqua Anio Vetus
In this area of the big bridges the aqueducts had winding tours to cope with the hilly terrain. This
cross-section is part of the original course of the Aqua Anio Vetus. Hadrian shortened the route with
the Ponte San Gregorio / di Mola, in line with Frontinus' remarks (De Aquis 18). This shortcut resulted
in a level jump of 3 m, which can be observed by the lower end of the bridge, see Ashby 1935, fig. 2