Cities in the United States remain on high alert before a special day of ceremonies to mark the 10th anniversary of the September the 11th attacks. On the eve of the anniversary US President Barack Obama paid tribute to those who died in the terror attacks 10 years ago and those who tried to save their lives. President Obama and his wife Michelle also visited the Arlington National Cemetery, paying their respects to the US military personnel who died in the wars in Iraq and Afghanistan. They comforted others who were visiting the grave sites. The President said United States is stronger than it was ten years ago, and that al-Qaida, which conducted the attacks, is on the path to defeat. Relatives of victims gathered in a field in Pennsylvania to watch the former President George Bush and current Vice-President Joe Biden unveiled a memorial to those who died in one of the hijacked planes.