WrestleMania is considered World Wrestling Federation's (WWF, now WWE) flagship event, having first been held in 1985. It has become the longest-running professional wrestling event in history and is held annually between mid-March and mid-April. It was the first of WWF's original four pay-per-views, which includes Royal Rumble, SummerSlam, and Survivor Series, which were eventually dubbed the "Big Four". It eventually became described as the Super Bowl of sports entertainment.