Just as the five cities of Colchester, Lincoln, York, Gloucester, and St. Albans, stand on the sites and in some fragmentary measure bear the names of five Roman municipalities, so Isca Dumnoniorum, now Exeter, appears to have been a cantonal capital developed out of one of the great market centres of the Celtic tribes, and as such it was the most westerly of the larger Romano-British towns. The legendary history of the place, both temporal and ecclesiastical, goes far back to the days when, for a late posterity, it is difficult to separate fact from fable. It is, however, quite established that here was the capital of the Dumnonii, the British tribe whose dominions included both Devonshire and Cornwall, and who named their capital Caer-uisc, the city of the waters.