Founded around the eighth century B.C., Rome conquered the Italian peninsula and came to dominate the Mediterranean by the second century B.C. Julius Caesar's conquest of Gaul in the first century B.C. led to the establishment of the Roman empire.

The ruins of Ancient Rome are known around the world, from the Colosseum, where as many as 80,000 spectators watched gladiators fight, to the Forum, the site of parades, elections, and trade, to the Pantheon, a temple that has still the world's largest unreinforced concrete dome.

Rome grew to larger than 1 million people by 1 B.C. It remained the world’s largest city until the fourth century, when the Western Roman empire crumbled.