The ancient Roman structure renowned for its massive amphitheater and gladiatorial games is the Colosseum. Completed in AD 80 under the Emperor Vespasian, it could hold tens of thousands of spectators and hosted a variety of public spectacles, including gladiatorial contests, animal hunts, and dramatic reenactments. The Colosseum served as a symbol of the might of the Roman Empire and remains an architectural marvel, influencing amphitheater designs in later cultures. It is a popular tourist destination today, reflecting Rome's rich history.