However that may be, there is ample proof that the site of the Castle at any rate was occupied by the Romans, for the remains of a fosse and vallum, forming part of an oblong enclosure within which the Castle Hill, whether early British or later Saxon, is included, seem to indicate the position of a Roman station here. Moreover, to this place converge the two great Roman roads, of which the remains may still be traced: _Akeman Street_, leading from Cirencester (Corinium) in the south through Hertfordshire to Cambridge, and thence across the fen (by the Aldreth Causeway, the scene of William the Conqueror's two years' campaign with Hereward) to Ely, and so onwards to Brancaster in Norfolk; and the _Via Devana_, which, starting from Colchester (Colonia or Camelodunum), skirted the forest lands of Essex through Cambridge and Huntingdon (Durolifons) northwards to Chester (Deva). Whether the Roman station, however, at the junction of these two roads can be identified as the ancient Camboritum is still a little doubtful. Certainly the common identification of Cambridge with Camboritum, because of the resemblance between the two names, cannot be justified. That resemblance is a mere coincidence. The name Cambridge, in fact, is comparatively modern, being corrupted, by regular gradations, from the original Anglo-Saxon form which had the sense of Granta-bridge. The name of the town is thus not, as is generally supposed, derived from the name of the river (Cam being modern and artificial), but, conversely, the name of the river has, in the course of centuries, been evolved out of the name of the town.[5] To return, however, to the Castle Hill. It may be doubtful, as we have said, whether the Roman station there was Camboritum or not, but there can be no doubt that the station, whatever it may have been called by the Romans, must have been a fairly important one, not only as commanding the open pass-way between the forest and the fen leading into East Anglia, but also as standing at the head of a waterway leading to the sea. It is difficult, of course, to estimate the extent of the commerce in these early days, or even perhaps to name the staple article of export that must have found its way by means of the fenland rivers to the Continent, but that it must have been at times considerable we may at least conjecture from the fact that in the records of the sacking of the Fenland abbeys--Ely, Peterborough, Ramsey, and Crowland--by the Danes in the seventh century there is evidence of a great store of wealth, costly embroideries, rich jewels, gold and silver, which can hardly have been the product of native industry alone, but seem to indicate a fair import trade from the Continent.