The ancient structure located in Rome that was used for gladiatorial contests is the Colosseum, also known as the Flavian Amphitheatre. Constructed between 70-80 AD, the Colosseum showcases remarkable Roman engineering and architecture, being one of the largest amphitheaters ever built. It could hold about 50,000 spectators who would gather to watch gladiators fight, public spectacles, and other forms of entertainment. The Colosseum remains an iconic symbol of ancient Rome and continues to be a popular tourist attraction, epitomizing the grandeur and complexity of Roman culture and its historical significance.