By Emily Kawamoto
1. The Colosseum is one of the largest amphitheaters ever built, with a seating capacity of up to 80,000 spectators.
Gladiatorial contests, where fighters battled each other or wild animals, were the most popular events held in the Colosseum.
Underneath the arena, a complex network of tunnels and rooms known as the "hypogeum" served as a backstage area for gladiators and housed various props.