As to when and where the first bridge spanned the Thames are points difficult to decide. Sir George Airy supposes that the bridge mentioned by Dion Cassius (43 A.D.) at the mouth of the Thames was not far from the site of London Bridge, on the inference that the mouth of the Thames of early times was close to this site. Dr. Guest, on the other hand, recognises it as a bridge made by the Britons, but places it as being constructed over the marshy valley of the Lea, near Stratford, his theory being that the Britons would have been unable to bridge over a tidal river like the Thames with the width of three hundred yards, and a difference of nearly twenty feet in the rise and fall of the water. From remains found of ancient piles in the river-bed, and the great number of Roman coins, a well-known practice observed by this Latin race to commemorate any important undertaking, antiquarians seem to agree that there was a Roman bridge in the Anno Domini period of their occupation, and that indications point to its location at London Bridge. In their time London was a port of considerable importance. As many as eight hundred vessels are said to have been employed in exporting corn alone in the year 359, which shows that agriculture was in full swing. With the departure of the Romans in 409 the city became the capital of the Saxon kingdom of Essex, and was called Lundenceaster. Subsequent events of importance are those that occurred under the dynasties of the Norman (1066-1154), the Plantagenet (1154-1485), the Tudor (1485-1603), the Stuart (1603-1714), interrupted in the midst by Cromwell's Protectorate, and finally the Hanoverian succession, which brings us down to this year of grace, with Edward VII., King of Great Britain and Ireland, Emperor of India, and monarch of the greatest and most prosperous empire. To attempt to give a detailed account of all that happened under the successive heads of the State is clearly impossible. Two events, however, stand out prominently. One was the Great Plague of London that commenced in December 1664, and carried off a matter of ninety thousand victims. The horrors of this pestilence are graphically described in the Diary of Samuel Pepys, who was an eye-witness. Daniel Defoe, though writing some years after, has given us a wonderfully realistic account in his "History of the Plague." Fires were kept up night and day, to purify the air, for three days. No sooner did the infection come to an end than the great conflagration of September 2, 1666, broke out. It began at one o'clock in the morning in a baker's shop in Pudding Lane, behind Monument Yard. It spread from the Tower to the Temple Church of the Middle Temple in Fleet Street, and away to Holborn. In the short space of four days it destroyed eighty-nine churches (including St. Paul's), the city gates, the Royal Exchange, the Custom House, Guildhall, Sion College, and many other public buildings, besides some fourteen thousand houses and the ruin of four hundred streets. The Monument, built by Wren in 1671-1672, commemorates the origin of the fire, 202 feet from its base.