According to the Astronomical Diaries, a collection of Babylonian texts in which astronomical observations and political events are recorded, Alexander the Great died on June 11, 323 BCE. Alexander marched to Babylon, where he drank heavily at many banquets, and became feverish.
He declined rapidly over the next few days, and died of the fever at the age of 33.
Since it is unusual for a healthy young man to die of natural causes, scholars have proposed many theories about the cause of death, but it will apparently remain shrouded in mystery forever.