The Roman Empire (Latin: Imperium Rōmānum, Classical Latin: [ɪmˈpɛ. ri. ũː roːˈmaː. nũː]; Koine and Medieval Greek: Βασιλεία τῶν Ῥωμαίων, tr. Basileia tōn Rhōmaiōn; Italian: Impero romano) was the post-Roman Republic period of the ancient Roman civilization. It had a government headed by emperors and large territorial holdings around the Mediterranean Sea in Europe, Africa and Asia. The city of Rome served as its capital until the seat of the imperial government was shifted to Constantinople by Constantine the Great in the 4th century AD.