London probably soon sprang, phoenix-like, from the fire, though history leaves it in darkness to enjoy a lull of 200 years. In the early part of the second century Ptolemy, the geographer, speaks of it as a city of the Kentish people; but Mr. Craik very ingeniously conjectures that the Greek writer took his information from Phoenician works descriptive of Britain, written before even the invasion of Caesar. Theodosius, a general of the Emperor Valentinian, who saved London from gathered hordes of Scots, Picts, Franks, and Saxons, is supposed to have repaired the walls of London, which had been first built by the Emperor Constantine early in the fourth century. In the reign of Theodosius, London, now called Augusta, became one of the chief, if not the chief, of the seventy Roman cities in Britain. In the famous "Itinerary" of Antoninus (about the end of the third century) London stands as the goal or starting-point of seven out of the fifteen great central Roman roads in England. Camden considers the London Stone, now enshrined in the south wall of St. Swithin's Church, Cannon Street, to have been the central milestone of Roman England, from which all the chief roads radiated, and by which the distances were reckoned. Wren supposed that Watling Street, of which Cannon Street is a part, was the High Street of Roman London. Another street ran west along Holborn from Cheapside, and from Cheapside probably north. A northern road ran by Aldgate, and probably Bishopsgate. The road from Dover came either over a bridge near the site of the present London Bridge, or higher up at Dowgate, from Stoney Street on the Surrey side.