London has a population of over 7,000,000. From about the year 1800 until World War II, London was the biggest city in the world. But now there are many cities which are much bigger than it. London is famous for many things. Tourists come from all over the world to visit its famous buildings and hear the famous clock, Big Ben. Like many big cities, London has problems with traffic and pollution which stop the city from developing. Over one million (百万) people a day use the London underground, but there are still too many cars on the streets. The air isn't clear, but it is anyhow cleaner than it was 100 years ago. For me, the best things about London are the parks. There are five in the city center. But my children's favorite place is Hamleys, the biggest toy shop in the world.