Today much of it is paved over with tar or gravel. It remains a major highway for the Levant.
Herod needed a port city to ship the wine, olives, and other produce back to Rome and other cities. There was only straight beach front, but Herod sunk barges of rock covered with Italian pumice, and that made an early marine cement. In a few short years there was a functioning harbor. Herod named it after the Roman emperor, and when the Romans took over Israel it became the provincial captital, sitting right on top of the Via Maris.