2011: Malta votes on the introduction of divorce; the proposal was approved by 53% of voters, resulting in a law allowing divorce under certain conditions being enacted later in the year.
2002: The last steel girder is removed from the original World Trade Center site. Cleanup duties officially end with closing ceremonies at Ground Zero in Manhattan, New York City.
1999: In Milan, Italy, after 22 years of restoration work, Leonardo da Vinci's masterpiece The Last Supper is put back on display.
1998: Nuclear testing: Pakistan responds to a series of nuclear tests by India with five of its own codenamed Chagai-I, prompting the United States, Japan, and other nations to impose economic sanctions. Pakistan celebrates Youm-e-Takbir annually.
1995: The 7.0 Mw Neftegorsk earthquake shook the former Russian settlement of Neftegorsk with a maximum Mercalli intensity of IX (Violent). Total damage was $64.1-300 million, with 1,989 deaths and 750 injured. The settlement was not rebuilt.
1987: A West German pilot, Mathias Rust, who was 18 years old, evades Soviet Union air defenses and lands a private plane in the Red Square in Moscow, Russia. He is immediately detained and released on August 3, 1988.
1961: Peter Benenson's article The Forgotten Prisoners is published in several internationally read newspapers. This will later be thought of as the founding of the human rights organization Amnesty International.
1937: Volkswagen (VW), the German automobile manufacturer is founded.
1936: Alan Turing submits On Computable Numbers for publication.
1934: Near Callander, Ontario, Canada, the Dionne quintuplets are born to Oliva and Elzire Dionne; they will be the first quintuplets to survive infancy.
1932: In the Netherlands, construction of the Afsluitdijk is completed and the Zuiderzee bay is converted to the freshwater IJsselmeer.
1588: The Spanish Armada, with 130 ships and 30,000 men, sets sail from Lisbon, Portugal, heading for the English Channel. (It will take until May 30 for all ships to leave port.)
621: Battle of Hulao: Li Shimin, the son of the Chinese emperor Gaozu, defeats the numerically superior forces of Dou Jiande near the Hulao Pass (Henan). This victory decides the outcome of the civil war that followed the Sui dynasty's collapse in favour of the Tang dynasty.
585 BC: A solar eclipse occurs, as predicted by the Greek philosopher and scientist Thales, while Alyattes is battling Cyaxares in the Battle of Halys, leading to a truce. This is one of the cardinal dates from which other dates can be calculated.