What things make Constantine an important figure in Rome's history?

Answer 1

Constantine was an emperor in a four-emperor co-emperorship called the tetrarchy (rule by four). He became the emperor of the western part of the Roman Empire after winning a war on an usurper emperor. In 324 he became sole emperor after wining a war against the emperor of the eastern part of the empire. Constantine is known mainly for being the first Roman emperor who supported Christianity. In 313. together with his co-emperor Licinius, he issued the Edict of Milan, which aimed at completing the ending of the Great Persecution of Christians which had been decreed by the Edict of Toleration by the emperor Galerius of 311. He tried to arbitrate disputes between rival Christian doctrines by holding synods and ecumenical councils, the most important of which was the First Council of Nicaea. He built a number of Christian churches, most notably the original St Peter's Basilica (Old St Peter's) and the Lateran archibasica (which was the first papal residence) in Rome, Church of the Holy Sepulchre in Jerusalem and the Church of the Holy Apostles in Constantinople . He also opened high office in the imperial administration to Christians.