The major turning point for the Roman Empire in the year 330 AD was the establishment of Constantinople (modern-day Istanbul) as the new capital by Emperor Constantine the Great. This strategic move reflected a shift in political power from Rome to the eastern provinces, allowing for better defense and administration of the empire. Constantinople became a vital cultural and economic hub, influencing trade and communication across Europe and Asia. The establishment of this city also signaled the beginning of the Byzantine Empire, which would endure for nearly a thousand years after the fall of the Western Roman Empire.