Until 2013, which country celebrated Queen's Day on April 30, the birthday of Queen Juliana?

In April 1956, which ruler of Monaco married American film star Grace Kelly? April 21 is a Rastafarian holiday marking Ethiopian emperor Haile Selassie's 1966 visit to which island? April 22, Earth Day, is also the birthday of which leader of the 1917 Russian Revolution? April 29, the birthday of Emperor Hirohito, is a national holiday in which Asian country? Which hard rock band, famous for "Welcome to the Jungle", played Farm Aid IV at Indianapolis's Hoosier Dome in April 19… Which Spanish-born artist died in France on April 8, 1973, at age 91? On April 9, 1865, which two generals met at Appomattox Court House to end the fighting in Virginia? U.S. ambassador April Glaspie held a controversial meeting with Saddam Hussein on July 25, 1990, while serving in which…