February 23: on this day in history

Historical events

1. 532Byzantine Emperor Justinian I laid the foundation stone of Hagia Sophia in Istanbul.
2. 1455According to the traditional account, the Gutenberg Bible, the first Western book printed with movable type, was published.
3. 1905Paul Harris and three businesspeople founded the world's first Rotary Club in Chicago.
4. 1927Werner Heisenberg first described the uncertainty principle in a letter to Wolfgang Pauli.
5. 1954Children in Pittsburgh received the first mass vaccinations with Jonas Salk's polio vaccine.

More days in February

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