The central part of london is full of historical remains. nearly every building, every bridge, every street, palace, house, and stone — each of them has its own story, its own past. in london past and present are so mixed together that they cannot easily be separated and when you are in london you see the past in the present and the present in the past. the oldest part of london is called the city. in the city the streets and pavements are very narrow and the traffic is very heavy on weekdays. that is because the most important london firms and banks have offices there. but at weekends the city is almost dead.