The storm of the U. S. Capitol would be the most shocking one, probably, as nobody dared to do that.
Also, 9/11 events, nuclear/thermonuclear bombs, nuclear power plant disasters, many things.
Technologically, the fact that an everyday laptop can deliver tens of billions of arithmetic instructions per second is still mind-boggling to me.
I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones. ~ Albert Einstein