Efforts to defuse the bomb failed and experts decided to pack it with explosives and detonate it rather than risk an uncontrolled explosion. Allied airplanes dropped millions of tons of ordnance on Germany during World War II in an effort to cripple the Nazi war machine. Tens of thousands of unexploded bombs are believed still to be lying in the ground in Germany.

This combination photo taken from a video shows the controlled detonation of the remains of a 550-pound World War II bomb in central Munich, Tuesday, Aug. 28, 2012. Efforts to defuse the bomb failed and experts decided to pack it with explosives and detonate it rather than risk an uncontrolled explosion.