It has been noticed that the masonry of the walls of the Roman houses seems to have finished not far above ground as if in preparation for timbering; other indications of this have been found, and a rough scratching of a house on a tile shows timber construction. This has recently been confirmed by the discovery at Silchester of houses which had timbered framing covered with clay daubing over wattle work, the outside surface being ornamented with zigzag patterns like mediæval pargeting, all of brick-red colour. Before the Roman forces were drawn back to the heart of the empire, London seems to have grown into the position of British Metropolis. Its position in regard to the arterial roads when the itinerary was compiled, shows how it tended to take precedence over the more military centres. Moreover, while the mint marks of one or two British cities appear on coins earlier than the mark of London, in Constantinian days London is the only British city where money seems to have been coined.[220] In the last days of the occupation the city had acquired the name of Augusta. We cannot doubt that the Roman soldiers drawn away to protect their lines of communication marched Romeward with the intention of returning again to the city by the Thames when the barbarian Germans and Goths had been thrust back into their woods and plains; yet the day of Rome was done, and their retreat was itself an incident in the advance of a new age. APPENDIX ON MATERIALS FOR THE CONSTRUCTION OF MAPS OF EARLY LONDON