ROMAN FRANCE - Julius Caesar's GAUL

One afternoon I drove through a series of long tunnels north of Nice to La Turbie, a medieval village hugging the hills 1,600 feet above the Mediterranean. Here, where the Alps jut sharply down to the sea, the Romans built a section of their new highway in 12 B.C. Surveyors, engineers and construction crews improved and linked paths that had existed since the time of the Greeks, cleaving passes through the mountains, introducing a sophisticated drainage system, erecting milestones and standardizing the road width to 15 feet—wide enough for two chariots to pass. It wound along the rugged coast to Fréjus, then cut across fertile plains to the Rhone. There, the thoroughfare merged with the Via Domitia, running west through the Spanish Pyrenees. When the two roads met—a convergence comparable to the 1869 linking of the Union Pacific and Central Pacific railroads at Promontory Summit, Utah—Roman control over the Mediterranean basin was cemented.

The Romans commemorated the feat with a victory monument at La Turbie, placing, in 7 B.C., a statue of Augustus on a limestone cylinder surrounded by 24 Doric columns. This is what I had come to see: I hiked along a wooded footpath to a hilltop clearing, from which the 115-foot-high Tropaeum, or Trophy, of Augustus—still partially standing after two millennia—dominates the landscape. The emperor's statue has disappeared, and only four of the marble columns that encircled the monument remain intact. One side of the great marble base features reliefs of winged deities flanking a Latin inscription that hails Augustus and the pacification of Gaul. Sheltering myself from a fierce wind, I gazed down the rocky coast of Italy; directly below, the hotels and villas of Monaco glittered at the edge of the turquoise sea. It seemed a fitting place to proclaim Rome's glory.

The Via Julia Augusta, as the highway was initially called, greatly improved overland travel in the empire. Roman legions could shuttle long distances along it at an average speed of almost four miles per hour. Messengers could travel between Arles and Rome, a distance of about 550 miles, in a mere eight days. "The highway was a means for Rome to assert its power," curator Martin told me. "Its real purpose was to move troops and public couriers at the fastest rate possible." By the third century A.D., the highway was known as the Via Aurelia and regarded as an extension of the empire's road from Rome to Pisa, commissioned in 241 B.C. by the censor Caius Aurelius Cotta.