According to Von Hagen, the most enduring monuments of Rome are the Roman roads

It is the massive grandeur of these stone-laid highways that lead out to the most remote horizons which is Rome's monument.

• Those Roman viae—each like a gigantic thread weaving together all the then-known world, stiching city to city—moved unerringly across mountains, over marshes and into the Sahara to link up with the fortresses guarding the limes (an ancient Roman frontier fortification or Roman wall marking the boundaries of the Roman Empire) of North Africa.
• These were not mere highways of laminated strata indifferently constructed, but highways precisely laid—inlaid, as it were, with pavements of massive stones, the underside of which was shaped like a diamond, truncated so as to be set into a yielding bed of gravel-sand.
• It is not possible to overrate the value of these great viae in the history of man's development.
• Rome became a mobile civilization and the mistress of the world because of her systematic control of world-space through her roads.
• From out of the Forum, from the "Golden Milestone" on which distances were recorded, paved roads led to every province.
• These continuous, well-engineered public roads went to the Rhine and the Danube, they flowed into the lands of the Scythians huddling around the edge of the Black Sea, to the Euphrates, to Africa, to Arabia and even along the outside edge of India, that great wedge of subcontinent.
• Twenty roads issued from Rome.
• These twenty developed, throwing out sideroads and laterals growing and multiplying in space and time, until during the reign of Diocletian, Rome was administrating 372 distinct roads.
• These 53,000 miles of communications were tight strings of civilization, great life-lines that went off to the edge of every horizon.
• The Roman engineers did not evade nature, they conquered her; if they met a river it was bridged; if a marsh intervened, the road became a causeway.
• The road zig-zagged over the Alps, but when rock became dominant it was tunnelled.
• Road building went on for eight hundred years until, as it must for all empires, the end came.
• By that time, Rome had paved the world.

Roads That Led to Rome, Part II is next.