Archaeological evidence supports the view that Rome grew from pastoral settlements on the Palatine Hill built in the area of the future Roman Forum. While some archaeologists argue that Rome was indeed founded in the middle of the 8th century BC, the date is subject to controversy.[8] The original settlement developed into the capital of the Roman Kingdom (ruled by a succession of seven kings, according to tradition), and then the Roman Republic (from 510 BC, governed by the Senate), and finally the Roman Empire (from 27 BC, ruled by an Emperor). This success depended on military conquest, commercial predominance, as well as selective assimilation of neighbouring civilizations, most notably the Etruscans and Greeks. From its foundation, Rome was undefeated in war, although losing occasional battles, until 386 BC when Rome was occupied by the Celts (one of the three main Gallic tribes), and then recovered by Romans in the same year.[9] According to the history, the Gauls offered to deliver Rome back to its people for a thousand pounds of gold, but the Romans refused, preferring to take back their city by force of arms rather than ever admitting defeat.

Roman dominance expanded over most of Europe and the shores of the Mediterranean Sea, while its population surpassed one million inhabitants. For almost a thousand years, Rome was the most politically important, richest and largest city in the Western world, and remained so after the Empire started to decline and was split, even if it ultimately lost its capital status to Milan and then Ravenna, and was surpassed in prestige by the Eastern capital Constantinople.