Rome did not conquer its empire and then build roads to administer it. The roads and the conquest advanced together, each enabling the other in a feedback loop that eventually produced the most extensive road network the ancient world had ever seen. At its peak, the Roman road system covered somewhere between 250,000 and 400,000 kilometers, of which roughly 80,000 kilometers were stone-paved primary roads capable of moving legions, supplies, and official communications at speeds that would not be matched in Europe until the nineteenth century.