This week, the Austrian National Library in Vienna displayed the Tabula Peutingeriana, or the Peutinger Table, to the public for one day. Unless you live in Vienna that news may not be of much significance, but it does provide an opportunity to discuss a rare and priceless object.
The Peutinger Table is actually a linen strip, some 20 feet long and about a foot and a half wide, that bears a road map of the Roman Empire and neighboring lands to the east. It is the only object of its kind, although we have literary texts called itineraries that list roads and the stops along them in a similar fashion. The first think one notices about the Peutinger Table is it's bizarre shape. The Mediterranean has been stretched out into a narrow blue stripe, and none of the shapes of the landmasses are recognizable. Nor is the map to scale. This is because the Peutinger Table is not so much a map as it is a visual list of roads, like the itineraries. Major cities are shown by small buildings (or, in the case of the largest cities, with more elaborate drawings), while the roads connecting them have small kinks in them to represent smaller settlements or stopping points. The distance between each stop is written in Roman miles, which is the most important information on the map. To a traveller, the exact relative position of, say, Massilia (Marseilles) and Rome was not important -- what was important is which roads led from the one to the other, and how far the journey was. The distance could be calculated by adding up the total mileage, or more likely by counting the number of stops and using that to calculate a duration in days (one, two, or three stops per day, depending on mode of travel).
The Romans in fact do not seem to have used proper scaled maps much at all, although there are some exceptions. The 3rd century marble city plan of Rome, hung in the Temple of Peace in what was probably the city deeds office, is drawn on a rough scale of 1:240, although it is hardly exact. On a smaller scale, the astronomer Ptolemy devised various projection systems to reduce the globe to a system of longitude and latitude lines, which in principle allowed the depiction of places in their true relative positions. Acquiring precise coordinates at that time was extremely difficult, however, and we don't have any evidence that his system was widely used in the construction of maps.
If you want to know more about the Peutinger Table, you don't need to go to Vienna. The entire map has been made available online. Check it out!