A combination of September 11, 2001 file photographs shows hijacked United Airlines Flight 175 as it approaches (upper L) and impacts the World Trade Center's south tower (L), bursting into flames and raining a hail of debris on lower Manhattan. A gaping hole in the north tower (R) can be seen following a similar attack earlier in the day. Monday, September 11, 2006, marks the fifth anniversary of the September 11 attacks on the United states, which claimed the lives of nearly 3,000 people. (Reuters)