Timeline of most important events in 20th and 21th centuries By Maria GV9 Nov 20, 1910 Mexican Revolution Jul 28, 1914 World War l Nov 7, 1917 The Russian Revolution and Communism Sep 28, 1928 Penicillin successfully used to treat a first patient Sep 1, 1939 World War ll 1956 First chemotherapy treatment Nov 9, 1989 The demolition of the Berlin Wall Sep 11, 2001 The 9/11 attack on the Twin Towers 2005 Facebook is formed by Mark Zuckerberg at Harvard 2015 Creation of the first artificial heart