What is the most devastating single terrorist attack in history?

[Il_Mostro]

If you do it it's war, if they do it it's terrorism.

[elscorcho768]

sirio, when you started this topic, did you intend it to become a debate over whether acts by the US constitute terrorist acts or did you actually want to know what the most devasting single terrorist attack was? If its the latter, you could probably look it up online or something.