US President George W. Bush and his wife Laura stood in somber silence on Sunday after laying wreaths at the ground zero site where the twin towers of the World Trade Center once stood. They honored the victims of the Sept. 11 attacks on a tour that will take them to all three sites of devastation on the fifth anniversary of the attacks. Accompanying them were New York Gov. George Pataki, New York Mayor Michael Bloomberg, and Rudy Giuliani, who was New York mayor at the time of the attacks. The Bushes also were to attend services at nearby St. Paul's Chapel. On Monday, the Sept. 11 anniversary, the president and first lady were to visit the Pennsylvania field where one of the hijacked planes hurtled to the ground, and the Pentagon crash site. Bush was to deliver a prime-time address Monday night from the Oval Office.