Some people may argue about this, but it as it was written:
"The kingsroad is the main overland route in the Seven Kingdoms and extends for almost two thousand miles. From the northernmost end at Castle Black, at the Wall, it runs south to Winterfell and then on through Moat Cailin and the only causeway through the Neck to the Ruby Ford to the capital at King's Landingand continues on through the Stormlands to Storm's End. It is not as impressive as the great Valyrian roads of the past, but overall it increases mobility and speeds of travel."
This is a good start in the comparison and setting up how big the lay of the land is.