Wikipedia:Selected anniversaries/May 11
- 330 - Byzantium became the new capital of the Roman Empire under Emperor Constantine I, and was referred to as Constantinople.
- 1792 - Explorer Robert Gray first sighted the Columbia River, the largest river flowing into the Pacific Ocean from North America.
- 1812 - British Prime Minister Spencer Perceval (pictured) was assassinated by John Bellingham in the lobby of the House of Commons.
- 1949 - Siam was officially renamed Thailand.
- 1960 - Mossad agents captured Adolf Eichmann, a Nazi leader and fugitive war criminal hiding in Argentina.