To the north of Roman London stretched vast primeval forests, and where St John’s Wood now stands, the wild boar roamed in trackless thickets. Marshes lay to the west and south, on the sites of Westminster and Southwark; a less likely place for the situation of a great capital, with the exception of St Petersburg, could not be found in Europe. On what is now Tower Hill stood a Celtic fortress, protected by the Thames on the south, and by forests and fens on the north. This fortress was admirably placed, protecting the approach from the seaward side of the river, and guarding against any attack from the land side. The Romans were evidently of this opinion, for after conquering the woad-stained Britons, they erected a fortalice, defended by strongly fortified walls, upon the same site. This Roman fortress was the origin of the Tower of London. Roman London, or rather Augusta, for so it was originally termed by the Romans, began at a fort named the Arx Palatina, overlooking the river a little to the south of Ludgate, a wall defended by towers, running in a south-easterly line along the river bank to another fort on the present site of the Tower, which was also named the Arx Palatina. Thence the wall took a northerly direction, reaching as far as the present Bishopsgate; it then turned due west to Cripplegate; then south by Aldersgate to Newgate, meeting the first wall at Ludgate. Roman London was indebted to the Emperor Constantine for these defences.[1] Theodosius is supposed to have restored this wall in the reign of Valentinian, but we have no further records of any work upon it until A.D. 886, when Alfred the Great repaired it as a protection against the Danish invaders.[2] The late Sir Walter Besant is my authority for saying “that there is a large piece of the Roman wall, extending 150 feet long, built over by stores and warehouses immediately north of the Tower, just where the old postern used to be, and where the wall abutted on the Tower.” It should be remembered, when judging of the circumference of the Roman wall, that London covered little more ground in those days than does Hyde Park at present: from Ludgate to the Tower the Roman wall extended only about a mile in length, and three and a half miles from the Tower to Blackfriars.