How old was Alexander the Great when he became the King of Macedon?

Alexander the Great was born in 356 BC and succeeded his father Philip II to the throne at the age of twenty. He spent most of his ruling years on an unprecedented military campaign through Asia and northeast Africa, and he created one of the largest empires of the ancient world by the age of thirty, stretching from Greece to northwestern India. He was undefeated in battle and is widely considered one of history's most successful military commanders.