The ancient Romans were sophisticated engineers, and consequently had well-defined units of measuring lengths and distances, and their relationships to each other are well known. However, no actual Roman standards are definitively known by the present day, so that the only way of determining the length of any Roman unit would be to measure something in modern terms whose length was given by the Romans in their units. The Romans were in the habit of putting mileposts on their roads, and these roads have, at least in some cases, survived to the present day, and thus a measurement of the distances they indicate (though requiring statistical treatment to allow for the inaccuracies of the Romans' own measurements) can be used to calculate the length of one unit, the Roman mile. (In fact, althou