By the late 3rd century BC, Rome had conquered the whole of Italy, and then defeated the Hellenistic Greek empires in a series of bloody wars. By the end of the 1st century BC, Rome had completed its conquest of the Mediterranean basin, before gradually swallowing a significant part of Europe beyond the Alps as well. This imperium spanned three continents, lasted half a millennium, and became one of the most successful states in history (1). Its roads organised from the centre still mark the main routes of Europe (2–3); Roman law gives models for modern states to follow. The Romance languages evolved from Latin, the use of which spread in Western and Central Europe following the Roman conquest (4).

The empire was composed of many peoples and diverse cultures. In its eastern provinces, Greek language and culture had been definitive for many centuries; in the western provinces Latin was universal, with Greek art spreading largely as a result of the Roman conquest. This difference outlined the two large geographical regions that later played a decisive role in the history of Europe. In 395 the eastern and western parts of the Empire became separated in a political sense (5). The Western Roman Empire came to an end in 476; while the Eastern Roman Empire and its successor-state, the Byzantine Empire, lasted another millennium, until 1453. In the 4th century, Christianity, formerly persecuted, became the state religion, while the influence of pagan cultural traditions continued for centuries. The world of late antiquity lasted until the Muslim conquest and the spread of Islam in the 7th–8th centuries AD.