At its height, the Roman empire covered some 5 million square kilometres and was home to around 60 million people. This vast territory and huge population were held together via a network of long-distance roads connecting places hundreds and even thousands of kilometres apart.
Compared with a modern road, a Roman road was in many ways over-engineered. Layers of material often extended a metre or two into the ground beneath the surface, and in Italy roads were paved with volcanic rock or limestone.
