Why did Constantine I choose Byzantium as the site for a new imperial capital?

Constantine I chose the site of Byzantium for his new imperial capital, which he inaugurated as "New Rome" or Constantinople in 330 CE, primarily for strategic and economic reasons rather than religious ones.1

The location offered several key advantages:

• Strategic Positioning: The site provided proximity to the critical Danube and Euphrates frontiers, allowing for better defense and military oversight of the empire's borders.1
• Economic Importance: The city was situated at the junction of major trade routes, including the vital continental road connecting Boulogne to the Black Sea, as well as eastern commercial paths passing through Anatolia toward Antioch and Alexandria.1
• Geographic Advantage: Its location where the Bosporus, the Golden Horn, and the Propontis meet made it a natural transit point between Europe and Asia.213

While Constantine initially considered Troy as a potential site, he ultimately selected Byzantium for its magnificent and highly functional location.2