On December 15:
- 1654: A meteorological office established in Tuscany began recording daily temperature readings.
- 1791: In the U.S., the first ten amendments to the Constitution, known as the Bill of Rights, went into effect following ratification by the state of Virginia.
- 2001: Leaning Tower of Pisa reopens
- 2009: UN’s climate chief thinks the negotiations at the Copenhagen summit are progressing too slowly.
