First off Alexander finished what his father started by uniting
Greece and giving all of Greece a common enemy. The one enemy that they shared was Persia. When Alexander's army showed up to Gaugamela they defeated one of Persia’s biggest army(BGE).. To conquer all of the land he killed roughly 100,000 people in all the wars he fought(DOC A). All this shows is how great he is because he was able to take down one of the biggest threats to Greeks.
After fight Persia, Alexander was able to make a huge empire. Once Alexander died his empire was at the size of 2,000,000 Square miles. When Alexander was creating his empire he founded 70 cities.(DOC E). When Alexander’s empire was at the height it reached from Greece to Egypt all the way to the border of India(DOC A). After Alexander Died his empire was able to last 10 years until everyone split apart(DOC E). All of this evidence shows hows great Alexander was because he was able to make a large empire and sustain it.