The mile zero of a Roman road, from which distances were counted, was always the crossing between the Cardo and the Decumanus, the two principal streets in every Roman town, running north–south and east–west respectively. In a section of the Tabula Peutingeriana, an ancient document showing the network of Roman roads, a river in northeastern Italy labeled ""fl. Rubicu"" is shown at a position 12 Roman miles () north of Rimini along the coastline; this is the distance between Rimini and a place called "Ad Confluentes," drawn west of the Rubicon, on the Via Aemilia. However, the river-bed shape observed in Pisciatello and the Rubicone river in the present day, well below Roman-age soil layers, is likely to indicate that any possible course modification of rivers could have occurred only very close to the coastline, and therefore only slight.