The ancient structure that served as a symbol of the power of the Roman Empire is the Colosseum, located in Rome. Also known as the Flavian Amphitheater, it was completed in AD 80 and could house tens of thousands of spectators. The Colosseum is emblematic of Roman engineering prowess and architectural innovation, featuring a complex system of vaults and arcs. It served as a venue for various forms of entertainment, including gladiatorial contests, animal hunts, and public spectacles, embodying the cultural and social dynamics of ancient Rome. The Colosseum remains a significant historical and tourist attraction today.