November 4

1333 – The River Arno flooding causing massive damage in Florence as recorded by the Florentine chronicler Giovanni Villani.

1966 – Two-thirds of Florence, Italy is submerged as the River Arno floods; together with the contemporaneous flood of the Po River in northern Italy, this leads to 113 deaths, 30,000 made homeless, and the destruction of numerous Renaissance artworks and books.

See : http://en.wikipedia.org/wiki/November_4.