Rome was founded by Romulus and Remus on seven hills along the Tiber River in Italy. Over time, Rome expanded from a small city-state to a vast empire that controlled lands across Europe and the Mediterranean. Key events in Roman history included the Punic Wars against Carthage, the transition from republic to empire under Julius Caesar, and the adoption of Christianity as the official religion. Roman achievements that influenced later societies included the republican form of government, the development of aqueducts and road networks, and the establishment of a system of laws.