C. 3.--The many relics of the Roman occupation to be seen in the Museum at the Guildhall bear further testimony to the commercial importance of the City in those early days, an importance primarily due, as we have already seen, to the natural facilities for crossing the Thames at London Bridge.[215] The greatness of Roman London seems, however, to have been purely commercial. We do not even know that it was the seat of government for its own division of Britain. It was not a Colony, nor (in spite of the exceptional strength of the site, surrounded, as it was, by natural moats)[216] does it ever appear as of military importance till the campaign of Theodosius at the very end of the chapter.[217] In the 'Notitia' it figures as the head-quarters of the Imperial Treasury, and about the same date we learn that the name Augusta had been bestowed upon the town, as on Caerleon and on so many others throughout the Empire, though the older "London" still remained unforgotten.[218] C. 4.--But, so far as Britain had a recognized capital at all, York and not London best deserved that name. For here was the chief military nerve-centre of the land, the head-quarters of the Army, where the Commander-in-Chief found himself in ready touch with the thick array of garrisons holding every strategic point along the various routes by which any invader who succeeded in forcing the Wall would penetrate into the land. At York, accordingly, the Emperors who visited Britain mostly held their court; beginning with Hadrian, who here established the Sixth Legion which he had brought over with him, possibly incorporating with it the remains of the Ninth, traces of which are here found. And here it remained permanently quartered to the very end of the Roman occupation, as abundant inscriptions, etc. testify. One of these, found in the excavations for the railway station, is a brass tablet with a dedication (in Greek) to _The Gods of the Head Praetorium_ [[Greek: theois tois tou haegemonikou praitoriou]], bearing witness to the essential militarism of the city.