A)THE ORIGINS
During the first centuries of the story of Rome there was only one connecting way between the city and the Etrurian lands: the road that, crossing the Tiber on the pons Sublicius, cut the plain beyond the Tiber near St. Cosimato and steeply climbed the Janiculum hill (green marked in pict.1); the pons Sublicius was moreover the only stable Tiber crossing.
The new needs of traffic and transport that the old bridge, wooden built for religious reasons, could no more sustain made necessary, around the VI century of Rome (II b.C.) a new solid bridge to better face the Tiber floods too.
The new bridge was built just upstream the pons Sublicius. According to tradition the construction of the pons Aemilius is attributed to the censors Marcus Aemilius Lepidu and Marcus Fulvius Nobilior that, within 181 and 179 b.C., built the stone piers to sustain a wooden footbridge, at the same time of the restoring of the portus Tiberinus that was located in place of the present Registry Office.
However at present it is considered more probable that the building of the bridge was already begun in 241 b.C. by a former member of the Aemilii Lepidi family (perhaps Manius Aemilius Lepidus Numida), in combination with the construction of the Via Aurelia (yellow marked in pict.1) by the censor Caius Aurelius Cotta. Consequently the structure completed in 179 b.C. should have been only a restoring of the damages caused by the flood.
In 142 b.C. the censors Publius Cornelius Scipio Emilianus (or Africanus Minor) (185 b.C. –129 b.C.) and Lucius Mummius Acaicus removed the wooden walkway and finally built six masonry arches on the five piers already existing across the river.
In the description of Aeticus in the Cosmographia Oceanus Occidentalis written in the century V the bridge is called Lepidi – that is "of Aemilius Lepidus", the manufacturer – and just after mangled by the people in the more concrete Lapideus, that is "built of stone".