Read the following article and answer the question. Article: London has more than nine million visitors every year. They come and visit some of the most famous places in England: Big Ben, the Tower of London and the River Thames. You can see some of the most interesting places in London by getting on the tour buses. Or you can take a ride on the London Eye. This large wheel slowly takes you 135m above the River Thames. The River Thames is London's main waterway. It has shaped the capital's _ history and geography. So one of the best ways of knowing more about the city is to take a trip along the river. The clock tower of the Houses of Parliament, Big Ben, has become one of the main symbols of London. The sound of the bell, which you can hear at the beginning of many television and radio programmes, has become well-known throughout the nation. No visit to London is complete without a look at the Tower of London, in the eastern part of the city. After Big Ben, the Tower may be London's most visited tourist spot. Directly south is Tower Bridge, which is more than100 years old. Along all the palaces in London, Buckingham Palace is the most famous. It has been the main London home of the royal family since Queen Victoria moved there in 1873. You can visit some of the rooms in August and September. And most mornings of the year you can watch the soldiers outside changing the guard. About one hour by train out of London is the Tower of Windsor. Here you can visit another of the Queen's homes-Windsor Castle. There was a fire in 1992 and many of the rooms were badly burned. But now they are full of beautiful pictures, tables and chairs again. Sightseeing in London is great, but it can get very tiring. So, the best way to start the day is to fill up with an English breakfast. You can buy an English breakfast in nearly every hotel, and at many restaurants and cafes. An English pub is a good place to stop for lunch and a drink. You can get hot or cold food and try one of England's many ales . Fish and chips are also a traditional English meal. So look out for fish and chip shops... Question: Which place may be London's most visited tourist spot? Answer:
Big Ben