The Alfred P. Murrah Building collapses into itself after being imploded on May 23, 1995 in Oklahoma City. Some 100 pounds of dynamite brought the building down in about 5 seconds. The April 19 explosion of a car bomb in front of the Federal building left 168 dead and 680 injured. Timothy McVeigh, convicted on first-degree murder charges for the 19 April bombing, the worst terror attack on US soil, was sentenced to death in 1997. (Photo by PAUL BUCK / AFP)(AFP/PAUL BUCK)