Here, at the beginning of the city, was instituted very early a ferry over the river. On the eastern hill the Romans built their forum and basilica, with the offices and official houses and quarters. When foreign trade began to increase, the merchants were obliged to spread themselves along the bank. They built quays and river-walls to keep out the water, and the city extended laterally to east and west, just as far as was convenient for the purposes of trade--that is, not farther than Fleet River on the west, and the present site of the Tower on the east. It then began to spread northward, but very slowly, because a mile of river front can accommodate a great working population with a very narrow backing of houses. When the city wall was built, somewhere about the year 360, the town had already run out in villas and gardens as far north as that wall. Outside the wall there was nothing at all, unless one may count a few scattered villas on the south side of the river. There was as yet no Westminster, but in its place a broad and marshy heath spread over the whole area now covered by the City of Westminster, Millbank, St. James's Park, Chelsea, and as far west as Fulham. Beyond the wall on the north lay dreary, uncultivated plains, covered with fens and swamps, stretching from the walls to the lower slopes of the northern hills, and to the foot of an immense forest, as yet wholly untouched, afterwards called the Middlesex Forest. Fragments of this forest yet remain at Hampstead, Highgate, Epping, and Hainault. All through this period, therefore, and for long after, the City of London had a broad marsh lying on the south, another on the west, a third on the east, while on the north there stretched a barren, swampy moorland, followed by an immense impenetrable forest. Later on a portion of the land lying on the north-west, where is now Holborn, was cleared and cultivated. But this was later, when the Roman roads which led out of London ran high and broad over the marshes and the moors and through the forest primeval. The point to be remembered as connected with the marshes is this: Around most great towns there is found a broad belt of cultivated ground protected by the wall and the garrison. Here the people grow for their own use their grain and their fruit, and pasture their beasts and their swine. London, alone among great cities, never had any such home farm until the marsh was reclaimed. The cattle, which were driven daily along the roads into the city, grazed on pastures in Essex farms, beyond the forest and the River Lea. The corn which filled her markets came down the river in barges from the inland country. All the supplies necessary for the daily food of the city were brought in from the country round. Should these supplies be cut off, London would be starved. [Illustration: BRONZE BUST OF THE EMPEROR HADRIAN: FOUND IN THE THAMES (_British Museum_)]