Alexander proceeded to Babylon, even after receiving word of several bad omens, such as ravens fighting each other over the city wall with some falling dead right in front of him, a man with a deformed liver being sacrificed in the king's honor, and his best lion was kicked to death by an ass. The god Serapis told a man to put on the king's robes and sit upon the throne. These all served as warnings to Alexander about what may lie in store for him, but they did not deter him.
Once in Babylon, he drank heavily at several banquets. One such banquet was hosted by his friend, Medius. In the Armenian version of the story, Psuedo-Callisthenes wrote that this banquet was a conspiracy involving Iollas, Cassander, and others who were unhappy with Alexander. They gave him poisoned wine, and immediately after drinking it, Alexander felt as if he had "been hit in the liver with an arrow." When he tried to throw it back up, he was given a poisoned feather, which ensured that the poison would reach his blood stream. He proceeded to get very sick and his condition deteriorated until his death. Plutarch did not believe this version, saying the sudden pain Alexander felt after drinking was a detail "with which certain historians felt obliged to embellish the occasion, and thus invent a tragic and moving finale to a great action. Aristobulus tells us that he was seized with a raging fever, that when he became thirsty he drank wine which made him delirious."
We will probably never know the truth, even though new theories are still coming out. We do know that on the 7th of June, 323 BC, the Macedonians were allowed to file past their leader for the last time and finally, three days later, he succumbed to the illness. Thus, on June 10, 323 BC, Alexander the Great died at the age of 33.