WrestleMania is considered WWE's flagship event, having first been held in 1985. It is the longest-running professional wrestling event in history and is held annually between mid-March to mid-April. It was the first of WWE's original four pay-per-views, which includes Royal Rumble, SummerSlam, and Survivor Series, dubbed the "Big Four". It has been described as the Super Bowl of sports entertainment. It was the last WrestleMania to feature the World Heavyweight Championship, as the title was unified with the WWE Championship at December's event, with the latter being renamed to WWE World Heavyweight Championship.