The Colosseum opened in 80 A.D. It had 80 entrances. Over 9,000 animals were killed in the inaugural games. Men and women were gladiators. Several Roman emperors were gladiators. The last known gladiatorial fight was around 425 A.D because Constantine declared Christianity as the religion and fights with death were not tolerated. Constantine was emperor from 306 to 337 A.D. He was baptized on his deathbed.