The Via Herculia is known as such solely through inscriptions. Their distribution, near Ariano Irpino, Monteleone di Puglia, Zungoli, Vallesaccarda, Melfi, Lavello, Venosa, Castel Lagopesole, Sala Consilina, and Marsico Nuovo, indicates that the road followed a route from somewhere near Ariano Irpino at least as far as Grumentum, by way of Venosa and Potenza. Their contents show that it was made a via publica by the time of Diocletian and Maximian Herculius (hence, probably, the name Via Herculia), was repaired and restored by Maxentius in 311 (which might argue for an original construction fairly early in the reigns of Diocletian and Maximian), and continued to be maintained by Constantine, Flavius Victor, Jovian, and Theodosius and Arcadius. It is clear that it was an important road in the Late Empire as a centrally located north-south highway through the rugged terrain of south Italy.

Some uncertainty exists, however, about its precise location. Several different routes have been posited by various authorities, who have in most cases tried to utilise the evidence of the ancient sources so as to make the highway follow one or another passage through the mountains.