Constantine the Great was one of the most influential Roman emperors, who, in 312 AD declared tolerance for Christianity and convoked the First Council of Nicaea, which produced the statement of Christian belief known as the Nicene Creed. He is venerated as a saint in Eastern Christianity and his influence pushed Christianity towards mainstream culture. Through his efforts to combat inflation and reorganize the Roman army by introducing mobile units (comitatenses) and garrison troops (limitanei), he established a new gold coin - solidus - that became an important currency for European countries for more than 1000 years.

His legacy led to Constantinople becoming an imperial residence and later capital city of Byzantine Empire, setting up a transition from classical antiquity to Middle Ages. Constantinian dynasty stemming from him had considerable impact on political structures in Europe during High Middle Ages. Conversations about Constantine always result in opposing views but modern scholarship strives to form balanced assessments when evaluating his reign.