When we see the words "Celtic London" at the head of a chapter we naturally feel inclined to ask, "Was there such a place? Was there any Celtic London?" Although it is almost impossible to answer such a question by either "yes" or "no," it may be worth while to examine it briefly before passing on to the domains of authentic history. In the first place, there must have been some gathering of huts or houses, some aggregation of residences, to which a name could be applied, and it must have been important enough to retain its name after the Romans came-nay, to retain it even in spite of an attempt on their part to change it. But though we must accept the existence of a London in the old obscure period when something very like modern Welsh was the language of the south-eastern part of Britain, and though we know that London was situated on a river which also had a Welsh name, we do not know directly on which side of that river it stood, and have nothing for it but to apply to the problem what a great authority has described as an historical imagination, and try if we can find a sufficient number of geographical or topographical facts to reduce the problematic side of the questions involved; and so to leave certain points, certain pedestals, so to speak, of firm ground on which we may place the foundations of the greatest city the world has seen.