The Italian peninsula was settled by many different groups, including Greeks in the south and Etruscans in the north. The Etruscans built cities and expanded southward into central Italy, where they influenced the culture of the small town that was growing into the city of Rome. Rome prospered and expanded its own territories, establishing a republican government led by the Senate and broadening the base of power to address social conflicts. In a series of wars (most significantly, the Punic Wars) the Romans conquered the Mediterranean, creating an overseas empire that brought them unheard-of power and wealth, but also social unrest and civil war. The meteoric rise to power of the politician and general Julius Caesar in the first century B.C.E. led to his assassination, but his grandnephew Augustus finally restored peace and order to Rome. He assumed many of the traditional republican offices, but in actuality he turned the republic into an empire.

Augustus and his successors further expanded Roman territories, and by the second century C.E. the Roman Empire extended from Scotland in the northwest to Persia in the east and Egypt in the south. The city of Rome became the magnificent capital of the empire, increasingly adorned with beautiful buildings and improved urban housing. The Roman provinces and frontiers also saw extensive prosperity through the growth of agriculture, industry, and trade connections that extended to India and China. Christianity, a religion created by the followers of Jesus of Nazareth, spread across the empire, beginning in the first century C.E. Initially some Roman officials and emperors persecuted Christians, but gradually hostility decreased, particularly as Christianity modified its teachings to make them more acceptable to wealthy and educated Romans and developed institutions modeled on those of the Roman Empire. Emperors in the fourth century first allowed Christianity and then made it the official religion of the empire, one of many measures through which they attempted to solve the problems created by invasions and political turmoil. Their measures were successful in the East, where the Roman Empire lasted for another thousand years, but not in the West, where the Roman Empire ended in the fifth century.