单项选择题

Today, the Tower of London is one of the most popular tourist 1 and attracts over three million visitors a year.
It was originally used as a Royal Palace for the Kings and Queens of England 2 the time of James I who 3 from 1603 to 1625, but is best known as a prison and 4 place Tower. Within the walls of the Tower, princes have been murdered, traitors 5 , spies shot, and Queens of England 6 . One of the most famous executions was that of Anne Boleyn in 1536. She was the second wife of Henry Ⅷ. He wanted to 7 her because she could not give him a son, so he 8 her of adultery. She was tried and found guilty. She asked to be beheaded with a sword, 9 the usual axe, which can still be seen in the Tower.
The Tower was also the 10 of one of London"s most famous mysteries. King Edward IV died in 1483. His elder son, Edward, became king 11 his father"s death. Young Edward lived in the Tower, and the Duke of Gloucester, his protector, persuaded Edward"s brother, Richard, to come and live there so that they could play together. But then the Duke 12 that he was the new king, and he was crowned 13 the twelve-year-old Edward, 14 himself Richard Ⅲ. After that, the boys were seen less and less and 15 disappeared. It is said that they were suffocated in bed by pillows being 16 their mouths. It is believed that Richard Ⅲ 17 their deaths, although it has never been 18 . In 1674, workmen at the Tower discovered two skeletons which were taken away and buried in Westminster Abbey in 1678. The 19 were examined in 1933 and were declared to be those of two children,
20 the age of the Princes.