Constantine decided to work on the Greek city of Byzantium, which offered the advantage of having already been extensively rebuilt on Roman patterns of urbanism, during the preceding century, by Septimius Severus and Caracalla, who had already acknowledged its strategic importance. The city was thus founded in 324, dedicated on 11 May 330, and renamed Constantinopolis ("Constantine's City" or Constantinople in English). Constantinople would be the capital of the Byzantine Empire.
In 330, Constantine moved the seat of the Empire to Constantinople, which he founded as a second Rome on the site of Byzantium, a city strategically located on the trade routes between Europe and Asia and between the Mediterranean and the Black Sea.
In the winter of 330 BC, at the Battle of the Persian Gate northeast of today's Yasuj in Iran, the Persian satrap Ariobarzanes led a last stand of the Persian forces. As a result, Alexander consolidated control of half of Persia and captures its dynastic center.