We will go back to the beginning of all things--to the lie of the land on which London was planted. The reader, if he will consult that very admirable book, Loftie's _History of London_, will find in it a most instructive map. It shows the _terrain_ before the city was built at all. The river Thames, between Mortlake on the west and Blackwall on the east, pursued a serpentine way, in the midst of marshes stretching north and south. There were marshes all the way. At spring tides, and at all tides a little above the common, these marshes were under water; they were always swampy and covered with ponds; half a dozen tributary brooks flowed into them and were lost in them. They varied greatly in breadth, being generally much broader on the south side than on the north. On this side the higher land rose up abruptly in a cliff or steep hill from twenty to five-and-thirty feet in height. The cliff, as we follow it from the east, approached the river, touched it at one point, and then receded again as it went westward. This point, where the cliff overhung the river, was the only possible place where the city could have been founded. I call it a point, but it consisted of two hillocks, both about thirty-five feet high, standing on either side the little stream of Walbrook, where it flows into the Thames. On one of these hills, probably that on the west, was a small fortress of the Britons, constructed after the well-known fashion of hill forts, numberless examples of which remain scattered about the country. On the other hillock the Roman city, later on, was first commenced. [Illustration: ROMAN PAVEMENT: LEADENHALL STREET]