許多希臘的知識被羅馬吸收，它利用敵人的不團结從意大利嚮外擴張，唯一真正對羅馬的崛起的挑戰來自 腓尼基人的殖民地迦太基, 它被擊敗在公元前3世紀，這一事件標志羅馬統治的開始。羅馬首先被國王統治，後來是元老院共和(羅馬共和國), 最後在公元前1世紀成為帝國，受奧古斯都和繼任的獨裁者們的統治。羅馬帝國勢力在地中海,控製着沿岸所有國傢。它的北部邊界是萊茵河和多瑙河。在皇帝圖拉真 （公元2世紀）統治時，帝國領土達到了最大，控製着近似5，900，000平方公裏的陸地面積，包括不列顛, 羅馬尼亞和部分美索不達米亞。帝國帶來了和平，文明和中央政府對治下領土有效的管理，但是在3世紀一連串的內戰消弱了它的經濟和社會力量。在4世紀，皇帝戴剋理先和君士坦丁把國傢分成了東西兩部分。雖然戴剋裏先殘酷迫害基督徒，但是君士坦丁還是於313年在米蘭敕令中宣佈停止國傢支持的對基督教的迫害，從而為帝國之後於380年將基督教作為國教埋下伏筆，使天主教會成為一個重要的組織。
Much of Greek learning was assimilated by the nascent Roman state as it expanded outward from Italy, taking advantage of its enemies' inability to unite: the only real challenge to Roman ascent came from the Phoenician colony of Carthage, and its defeat in the end of the 3rd century BCE marked the start of Roman hegemony. First governed by kings, then as a senatorial republic (the Roman Republic), Rome finally became an empire at the end of the 1st century BCE, under Augustus and his authoritarian successors. The Roman Empire had its centre in the Mediterranean Sea, controlling all the countries on its shores; the northern border was marked by the Rhine and Danube rivers. Under emperor Trajan (2nd century AD) the empire reached its maximum expansion, controlling approximately 5,900,000 km² (2,300,000 sq mi) of land surface, including Britain, Romania and parts of Mesopotamia. The empire brought peace, civilization and an efficient centralized government to the subject territories, but in the 3rd century a series of civil wars undermined its economic and social strength. In the 4th century, the emperors Diocletian and Constantine were able to slow down the process of decline by splitting the empire into a Western and an Eastern part. Whereas Diocletian severely persecuted Christianity, Constantine declared an official end to state-sponsored persecution of Christians in 313 with the Edict of Milan, thus setting the stage for the empire to later become officially Christian in about 380 (which would cause the Church to become an important institution).