What two major decisions did Constantine make that affected the future of the empire?

Constantine made two pivotal decisions that significantly shaped the future of the Roman Empire: first, he established Constantinople (modern-day Istanbul) as the new capital in 330 AD, strategically positioning it for trade and defense, which ultimately led to the Byzantine Empire's prominence. Second, he embraced Christianity, issuing the Edict of Milan in 313 AD, which granted religious tolerance and set the stage for Christianity to become the dominant religion of the empire, fundamentally altering its cultural and political landscape.