There were 76 public doors which led to four different sections of the Colosseum, each for a different socioeconomic class. The best seats at the Colosseum were in the front row, located upon a podium raised 6.5 feet above the arena floor. Along the same podium sat the emperor in his box. Regardless, tickets weren't sold directly, though evidence suggests attendees still had assigned seating. Some historians believe, however, the tickets were paid through some other means, possibly with membership to certain clubs.
Admission into the Colosseum was free it was one of the many perks of being a Roman citizen.