768-Charlemagne and his brother Carloman I are both crowned King of the Franks 1000-Leif Erikson reaches "Vinland" (possibly L'Anse aux Meadows, Canada), reputedly becoming the first European to reach North America 1446-Korean hangeul alphabet is first published by King Sejong the Great 1941-U.S. President Franklin D. Roosevelt approves an atomic program that would become the Manhattan Project 1952-The construction of the United Nations Headquarters is completed in New York City 1970-Khmer Republic (Cambodia) declares independence 1974-Race riot in Boston due to "bussing" 2006-North Korea conducts its first nuclear test with an estimated yield of between 0.4 and 2 kilotons