Before the west end of London was built the Tower was in the important part of London. All that could then be called London clustered round it. In those days, when the country was unsettled and enemies appeared suddenly outside a town, and might burn and destroy houses, and steal all that they could lay hands on, it was necessary to have a wall all round the city. This wall was very strong and high, and could be defended by men with spears and arrows. It ran right round the city on three sides, and on the fourth was the river. In the reign of William the Conqueror there was no strong castle or palace for the King in London, but only an old fortress on one side of this wall, the east side, quite near to the river. This fortress had stood there for a long time. No one knew when it had been built. King William ordered it to be pulled down, and in its place he caused a strong castle to be built. Part of the city wall was pulled down to make room for this castle, and so began the Tower of London. If we, living in the West End, want to get to the Tower, we must take an omnibus or train and go right through the City until, at the place where the City and the East End meet, we shall find the Tower. It is a very fine building, with a great square tower in the middle. Round it are the gardens, and round the gardens, again, there is another line of buildings, which have smaller towers set here and there upon them at intervals. Circling round the outermost walls is a huge, deep ditch, as big and broad as a river. This was once a moat full of water. The water from the Thames ran into it and filled it, and it formed a strong barrier of defence for the Tower, and attacking forces would have found it a difficult matter to swim across that water with the archers and soldiers shooting down from the walls above, with flights of arrows as thick as flights of pigeons. And, of course, the enemies would never have been allowed to put a boat on the water, for the archers would have shot them while they were doing it. In old times the kings who lived here must have felt very safe with their huge thick stone walls and the great rolling stream of gray water all round. The windows were made very small, so that arrows could not get into them easily to wound the people inside the rooms, and the staircases were of stone, very narrow, and they wound round and round up into one of the towers. They were made so because then, if ever the enemies did manage to get inside the Tower and tramped upstairs, they would find that only one, or perhaps two, of them could get up the steps together to fight, and the men who were guarding the tower could keep them back for a long time. As I said also, the gardens are inside the Tower, so the people who lived there could walk safely in them surrounded by the great gloomy high stone walls. [Illustration: ST. MARY-LE-STRAND AND BUSH HOUSE.]