This picture was recently published in the Greek newspaper Kathimerini to show that Alexander the Great, who was a Macedonian, was also a Hellene. From a 16th century perspective, therefore, ancient Macedonia was a part of Hellas (Greece) and not a seperate nation as is commonly held by todays so-called Macedonians. The mural is dated to 1568 from the Monastery of Dochiariou on Mount Athos.
The exact inscription says for the left “Βασιλεύς Ελλήνων Αλέξανδρος” (Alexander King of the Hellenes) and on the right it says “Βασιλεύς Ρωμαίων Αύγουστος” (Augustus King of the Romans).
It should be noted that the term "Hellenes" in the mural refers to ethnicity and not the fact that they were idol worshippers, since Augustus, who even though called a Roman, was also an idol worshipper. Also, this is not the Emperor Alexander who ruled from 912-913 A.D. since this Emperor would not have been called a King of the Hellenes but rather "King of the Romans". No Roman Emperor ever called himself "King of the Hellenes". Furthermore, the Roman Emperor Alexander would have been out of place here since what is clearly being depicted are ancient Kings.
For more information, see here.