When the Romans completed the subjugation of the southern part of Britain and began to make settlements, their practical sagacity at once perceived the eligibility of this spot as a centre of commerce; and in a short time it put on the appearance of a Roman city, and gradually became adorned with residential houses after the Roman fashion—whose tesselated pavements and other decorations are still often exhumed—with marts of commerce, temples of the gods, basilicæ, baths, amphitheatres, and other architectural appliances of an important city.
At what period the Romans substituted a wall of defence in place of the old earthworks is uncertain, but previous to its construction they appeared to have erected two forts on the north bank of the Thames—one at the eastern extremity of the City, where the tower now stands; the other at the western end, where the Fleet fell into the Thames. That it was an open town, or very imperfectly defended, in the middle of the first century, is evidenced by the facility with which Queen Boadicea, temp. Nero, entered it with her army, slaughtered the inhabitants, and most probably burnt it, as the charred remains of a great conflagration have been frequently found in making deep excavations. Henry of Huntingdon, and some other of the old chroniclers, tell us that it was first walled by Constantine the Great, at the request of his mother Helena, and that the materials he made use of were hewn stone and British bricks, and that it was in compass about three miles. Camden seems to credit this statement, from the fact that coins of the Empress Helena have been found under the wall, but as these might have been in circulation long after her death, it only goes to prove that the wall was not built before her era. Constantine died in the year 337, and we find some twenty-five years afterwards London was entered and pillaged, and the inhabitants reduced to a state of great misery, by a combined army of Picts, Scots, Saxons, and Franks, which would scarcely have been possible if it had been walled, and defended by the disciplined soldiers of the empire. The probability seems to be that the walls were either built or commenced by Theodosius, the Roman general, afterwards emperor, who in the reign of Valentinian, came to Britain with an army, utterly routed the pirates and freebooters, and entered London in triumph, where he remained for a considerable period; and we are told by Ammianus Marcellinus that before he left the island he restored to their ancient sound condition both the towns and military strongholds throughout the country, and put everything in such a state of defence that peace was maintained until the reign of Honorius, when Britain was abandoned by the Romans. Hence we may arrive at an approximate date for the building of the walls. Constantine came to the throne in 306, and Valentinian died 375: and it is almost certain that it took place some time within these 70 years, the balance of evidence seeming to refer it farther to the period of the sojourn of Theodosius in Britain, or about 368-70.
Fitzstephen is the earliest writer who mentions the wall. He lived in the reign of Henry II., towards the end of the twelfth century, and describes the wall as high and thick, with seven double gates and many towers and turrets placed at proper distances. Originally there were only four exits from the City—by way of Aldgate on the east, Cripplegate on the north, Newgate on the west, and Dowgate on the south; the latter was the entrance to the "Trajectus," or ferry across the Thames, and derived its name from Dwr or Dour—water; or perhaps from Dwyr Dover, as leading to the Dover-road. Near to this gate was placed the Miliarium, a portion of which may still be seen in the wall of St. Swithin's Church, whence distances were measured along the roads, and from which radiated four roads—one by Dowgate and across into Kent, and three others which passed respectively through Aldgate, Cripplegate, and Ludgate. The wall commenced at the eastern fort, and had a postern gate at its commencement which occupied the position of the row of posts in Postern-row, north of the Tower, whence it ran northward to Aldgate, the eastern exit (some portions of the old wall are still remaining at the back of the houses in America Crescent); from Aldgate it went in a north-western direction between Hounds-ditch and Camomile Street to Bishopgate, whence it proceeded directly west to Cripplegate. In the street called London-wall a fragment may be seen, and the remains of a bastion may be found between St. Giles's Church and the Barber Surgeons' Hall. From this point it turned southward for a short distance down Noble Street, and again deflected to the west, arriving at Aldersgate, after which it passed St. Botolph's Church and Christ's Hospital, then turned southward at a sharp angle, coming to Ludgate (which stood immediately to the west of St. Martin's Church), and hence to the Thames. In 1276 that portion south of Ludgate was taken down, and a new wall built from Ludgate to the Fleet river, and hence south to the Thames, so as to enclose the new Blackfriars' Monastery. It has been doubted whether the wall was continued along the river bank, but Fitzstephen says:—"London once had its walls and towers on the south, but that vast river, the Thames, which abounds with fish, and enjoys the benefit of tides, and washes the City on this side, hath in a long track of time totally subverted and carried them away;" and adds, that in his day some relics might be seen. Salmon, in his Survey of England, vol. i., disputes this, chiefly on the ground that we have no historical account of any great inundation such as would be necessary to effect such a result; and Maitland combats his arguments at great length, contending that a period of 777 years was quite sufficient to account for their decay and disappearance; and Lord Lyttelton remarks that long previously it had not been necessary to repair the south wall, the Tower and the bridge being amply sufficient to prevent a hostile fleet approaching the City.
In the year 1707 considerable portions of the wall were laid bare in digging for the foundations of some houses near Bishopsgate, which Dr. Woodward carefully examined, and gave a description of the materials and construction in "Remarks upon the Ancient and Present State of London: Occasioned by some Roman urns, etc., discovered near Bishopgate," originally published in the eighth volume of Leland's Itinerary, and afterwards separately. He says: "It was compiled alternately of layers of broad flat bricks and of ragstone. The bricks lay in double ranges, and each brick being but one inch and three tenths in thickness, the whole layer, with the mortar interposed, exceeded not three inches. The layers of stone were not quite two feet thick of our measure. To this height (eight feet) the workmanship was after the Roman manner, and these were the remains of the ancient wall. In this it was very observable that the mortar was, as usual in the Roman work, so very firm and hard that the stone itself was easily broke and gave way as that. It was thus far from the foundation nine feet in thickness. The broad thin bricks above mentioned were all of Roman make, and of the sort, as we learn from Pliny, that were in common use among the Romans, being in length one foot and a half of their standard, and in breadth one foot. The old wall having been demolished, was afterwards repaired and carried up of the same thickness to eight or nine feet in height; or, if higher, there was no more of that work now standing. All this was apparently additional, and of a make later than the part underneath it. The outside, towards the suburbs, was faced with a coarse sort of stone, not compiled with care, nor disposed into a regular method; but on the inside there appeared more marks of workmanship and art. There was not one of the broad thin Roman bricks mentioned above in all this part, nor was the mortar near so hard as in that below; but from the description it may be easily collected that this part, when first made and entire, with so various and orderly a disposition of the materials—flint, stone, and bricks—could not but carry a very elegant and handsome aspect. Upon the additional work now described was raised a wall wholly of brick, only that it terminated in battlements topped with copings of stone. It was two feet four inches in thickness, and somewhat above eight feet in height.... This wall was strengthened and embellished with stately towers, which on the south, together with the wall, are long since become a prey to the tide and weather; but the remains of those on the land side, being fifteen in number, are still to be seen: one thereof, about the middle of Houndsditch, is a Roman construction, composed of stone with layers of bricks. It is situated almost opposite the end of Gravel Lane, on the west of Houndsditch, and is still three stories high, but sorely decayed and rent from top to bottom in divers parts."
The height of the Roman wall is supposed to have been about twenty-two feet, and that of the towers about forty. Besides these towers there were bastions and other defensive works usual in fortifications. In Vineyard Street, on the south of Aldgate, the base of a tower about eight feet high was made use of for a new superstructure early in the last century, upon which had been fixed a stone with this inscription: —
"Glory be to God on high, who was graciously pleased in a wonderful manner to preserve the lives of all the people in this house, twelve in number, when the ould wall of this Bulwark fell down three stories high, and so broad as two cartes might enter a breast, and yet without any harm to their persones. The Lord sanctify this his great providence unto them. Amen and Amen. It was Tuesday, the 23rd September, 1651."
There is reason for believing that the first western wall ran southward, with a slight inclination to the west, from Cripplegate to the Thames, passing eastward of St. Paul's, as urns and other sepulchral remains have been found between this line and that indicated above. The Romans never buried their dead within the walls, consequently this locality must at some period have been extramural; and it would appear that as these remains have been found beneath pavements, as the City grew in population and required more space for the habitations of the living, the old graveyards were built over. Some forty years ago, in sinking a shaft in Paternoster Row, the excavators met, at a depth of eighteen feet, a stone wall of such intense hardness that it took the workmen three or four days to cut through it. This is supposed to have been a portion of the primitive wall, and is described by C. Roach Smith in the Archæologist, vol. xxvii., pp. 140-53.
After the departure of the Romans, the wall appears to have fallen to decay, and the City was easily taken by the Saxon pirates, who also neglected defences of this description to a great extent, trusting more to their own valour than in bricks and mortar. It would no doubt suffer greatly in the destruction of its towers and bastions in the three great conflagrations which occurred in the years 764, 798, and 801, and consumed the greater part of the City. Such being the case, it fell an easy prey to the Danes, who in 851 sailed up the Thames with a fleet of 350 ships, speedily reduced it, and garrisoned it as a basis whence to attack Wessex. Alfred the Great succeeded to the throne of Wessex in 871, and from that period to 878 he fought no less than fifty-six battles with the invaders. In 884 he laid siege to London, drove out the Danes and compelled them to capitulate, after which he repaired the walls and forts, and appointed his son-in-law, Ethelred, governor. The repairs appear to have been of a substantial character, as when Anlaf and Swegen, or Sweyn, the kings of Norway and Denmark, attacked the City, with a fleet of 94 ships, in 994, the citizens were enabled to defy all their endeavours to enter within the walls, and compelled them to raise the siege with great loss, as happened again in 1013, when the city was defended by Ethelred II. But after some successes elsewhere, Sweyn returned, and again laid siege to the City; and again the citizens might have closed their gates against him, but Ethelred, their king, pusillanimously fled to Normandy, and the citizens deemed it best to submit, whereupon the gates were thrown open, the Danes admitted, and Sweyn proclaimed King of England.
Sweyn did not long enjoy this dignity; he died the following spring, when the Londoners recalled Ethelred: and he also dying soon after. Edmund Ironsides, his son, was proclaimed king, and crowned in London. Canute, the son of Sweyn, however, claimed the crown won by the prowess of his father, and came with a large fleet up the Thames, but could not pass beyond the bridge, and finding he could make no impression on the eastern walls and forts, he cut a canal across Southwark and Lambeth, availing himself of certain watercourses, and conveyed his ships into the Thames somewhere about Vauxhall, whence he sailed downward, and attacked the western walls and towers; but the undaunted bravery of the citizens and the strength of their defences compelled him to raise the siege. Soon after, however, a treaty was entered into between Edmund and Canute for the division of the kingdom: and London falling to the share of the latter, he took up his winter quarters there. By the death of Edmund a few months after, Canute became sole monarch of England.