Domesday Book gives the number of these as only 400, and a couple of centuries later, in 1279, when the University was already in full existence, there were scarcely more. By the middle of the eighteenth century this number had trebled. But even in 1801, as may be seen in Lyson's plan of the town, the King's Ditch, which was then still an open watercourse, remained substantially the boundary of inhabited Cambridge. And the vast suburban extensions in the areas of Barnwell, Newnham, Chesterton, and Cherry Hinton are mostly very recent indeed; the bulk in fact belonging to the last half century. Their rise, and the continuous intrusion of ever fresh University and College buildings, has had the effect of once more depleting the area of mediæval Cambridge, which to-day contains barely 800 houses. The whole of the University buildings, whether ancient or modern, are contained within this area, with the exception of the Colleges of Peterhouse, Pembroke, Christ's and Jesus (which together with a few of the Museums, stand just beyond the Ditch), and the New Court of St. John's College, which is on the other side of the river, in the old Common Field. The ecclesiastical and feminine foundations similarly situated, Selwyn College, Westminster College, Ridley Hall, Newnham College, and Girton College, are not recognised by the University as being strictly "Colleges" at all.

Peterhouse Wall, Coe Fen.

Such was old Cambridge; with its eleven ancient parishes of St. Peter, St. Giles, St. Clement, Holy Trinity, St. Michael, St. Mary (the greater), St. Edward, St. Benet, St. Botolph, All Saints, and St. John (which was destroyed to make room for King's College). Before the twelfth century closed three more churches were added, those of the Holy Sepulchre, of St. Peter (now St. Mary's the less) outside the "Trumpington Gate," of St. Andrew (the greater) outside the Barnwell Gate, and St. Andrew (the less) in the detached suburb which grew up round the great "Abbey" (really an Augustinian Priory) of Barnwell.

Old Cambridge probably owed its constitution—(quite possibly its very existence)—to the genius with which "the Children of Alfred," Edward the Elder and his Sister, the "Lady of the Mercians," reorganised the Midlands after the great cataclysm of the Danish wars, which in the previous generation had swept over the district, obliterating all earlier landmarks and boundaries. One pirate horde, under the most renowned of all their chieftains, Guthrum—the deadliest antagonist, and afterwards the most faithful ally, of our great Alfred,—had for a space settled themselves in Cambridge, and from that strategic position overawed East Anglia on the one hand and Mercia on the other.[2]

The Cambridge which they sacked was not, however, as it would seem, the later mediæval town which we have been already considering, but a much smaller stronghold on the western bank of the River, comprising what is now known as "Castle End," and is still sometimes called "the Borough" par excellence. At this point the Cam, one bank or other of which is usually swampy even now, and was actually swamp in early days, is touched by higher and firmer ground on both sides. The height to the west is quite respectable, rising some eighty feet above the stream. Here, therefore, and here alone, was there of old any convenient passage-way for an army; the river elsewhere forming an almost insuperable barrier to military operations, from the Fens almost to its source. Such a site was sure to be amongst the earliest occupied; and we find, accordingly, that both Romans and Anglo-Saxons (presumably Mercians) successively held it. Most probably it was also a British site; but the great Castle mound, which earlier antiquaries attributed to the Britons, has been shown by Professor Hughes to be, mainly at least, a Norman work.

This site was the original Cambridge, and may even have been called by that very name in its earliest form. For it is hard not to identify the Roman settlement (which the spade shows to have existed here) with the "Camboritum," which from the "Itinerary of Antoninus" (an official road book, probably of the third century A.D.) must have been somewhere in this immediate neighbourhood. And the word Camboritum is plausibly derived from the British Cam Rhydd "the ford of the Cam." Cam (which, being interpreted, signifies crooked) may well have been the British name for a stream with so tortuous a course. But, if so, it was not continuously used, so far as records can tell us.

The Roman Camboritum doubtless shared the almost universal destruction of Roman stations which marked the English conquest of Britain; and the site is described as still "a waste chester" two centuries later, when the monks of Ely sought amid the ruins for a stone coffin in which to entomb their foundress, St. Ethelreda. By this time the older name both of the town and of the river seems to have been forgotten. The latter was called, by the English, the Granta, and the former was accordingly known only as Granta-ceaster—the chester, or ruined Roman city, upon the Granta. (It should be noted that the village now called Grantchester was, till comparatively recent days, known as Grant-set.)

Yet another century, and we find, in the days of King Egbert, the grandfather of Alfred and the first King acknowledged by the whole English nation, that a bridge had been built (or rebuilt) over the old ford; and therewith the old site of Camboritum had been reoccupied under the new name of Granta-bridge, by which it is known throughout mediæval history. We do not meet with "Cambridge" in literature till the fourteenth century, nor with "Cam" till almost the date of "Camus, reverend sire," in Milton's Lycidas.