#1 - the fall of communism and the breakup of the USSR which freed hundreds of millions of people living under severe oppresion with no freedom of speech, no freedom of religion, etc, etc, and many thousands wh lived in slave labor camps in the Gulag. I met one of my distant relatives who was born and raised in a labor camp in Siberia.
#2 - man landing on the moon.
#3 - Woodstock - symbolizing the generation of the 1960's.