May 11 is the 131st day of the year according to the Gregorian calendar (132nd in the leap year). There are 234 days left until the end of the year.
1642 - The Swedes defeat the imperial army at the Polish town of Swidnica. This allowed them to penetrate Moravia.
1786 - The Bouda Theater is opened in the Horse Market in Prague.
1864 - The Czech Landtag approves a proposal for systematic scientific research in Bohemia. A group led by J. E. Purkyně took on the task.
1889 - The Czech Tourists Club creates the first marked Czech tourist route.
1945 - A meeting between the commander of the troops of the 1st UF, Marshal Ivan S. Konev, took place with government officials, where the first practical issues concerning the provision of assistance to the people of Prague and the entire republic were resolved.
1946 - The Prague Spring Festival is founded.
1949 - The law establishing the National Gallery in Prague is approved.
0330 - Roman Emperor Constantine I the Great renamed Byzantium Nova Nova (New Rome). After his death, it was renamed Constantinople.
0868 - The oldest known dated printed book is published, the Chinese translation of the Diamond Sutras.
0912 - Alexander becomes emperor of the Byzantine Empire.
1189 - Emperor Frederick I. Barbarossa takes command of the German part of the Third Crusade, and sets out with Regensburg with 100,000 crusaders.
1421 - Jews are expelled from Graz.
1573 - The Polish nobility elects Henry of Valois as King of Poland.
1608 - The Protestant Union is founded - one of the warring parties of the later Thirty Years' War.
1745 - Wars of the Austrian Succession: French forces defeat the Anglo-Dutch-Hanoverian army.
1792 - Robert Gray commands the first expedition to enter the Columbia River.
1812 - Prime Minister Spencer Perceval is assassinated by John Bellingham in the hall of the British House of Commons.
1813 - William Lawson, Gregory Blaxland and William Wentworth discover a route through the Blue Mountains and open a land inland Australia.
1846 - President James K. Polk demands that a war be declared against Mexico, which has begun a Mexican-American war.
1858 - The state of Minnesota is annexed to the United States.
1891 - During a visit to Japan, an unsuccessful assassination attempt is carried out on the Tsarevich and later Russian Tsar Nicholas II.
1910 - The Glacier National Park is established in Montana by an act of the US Congress.
1939 - Soviet-Japanese border conflicts: the Battle of Chalchyn River breaks out.
1943 - WWII: US troops invade Attu Island in the Aleutian Islands in an effort to drive out Japanese occupying forces.
1949 - The Southeast Asian state of Siam is renamed the Kingdom of Thailand.
1950 - The All-German CDU is founded. Konrad Adenauer became the first chairman.
1960 - Adolf Eichmann is captured by the Mossad in Argentina.
1985 - 56 spectators are killed and more than 200 are injured in a stadium fire in Bradford City.
1987 - Klaus Barbie is tried in Lyon for war crimes committed during World War II.
1996 - ValuJet Flight 592 crashes into the Everglades ten minutes after takeoff due to a fire caused by poorly stored dangerous cargo. All 110 people on board were killed.
1997 - Deep Blue, a supercomputer playing chess, defeats Garry Kasparov in the last rematch and becomes the first computer to defeat the world's best chess player in a classically formatted match.
1998 - India conducts three underground nuclear tests in Pokhran.
2000 - India's population reaches one billion.
2005 - Release of the popular video of World of Warcraft starring Leeroy Jenkins. 
2010 - David Cameron takes over as Prime Minister of the United Kingdom as Conservatives and Liberal Democrats form the country's first coalition government since World War II.