You know about the Black Sox scandal and have been regaled with tales of the veritable pitching machine named Cy Young. You've heard about Babe Ruth's called shot and about all the things that made Ty Cobb a splendid ballplayer and a hateful person. But when it comes to the origins of pro football, well, there's just nothing that compares with baseball lore. At the outset pro football was plagued by fan apathy and was slow to evolve into the game that became so popular. "For the longest time pro football was equated to pro wrestling in terms of national respect," says Wellington Mara, 83, the co-owner of the Giants and son of Tim Mara, who founded the franchise. What follows are eight landmarks, one from each decade from the 1920s through the '90s, that mark the evolution of the NFL into the most successful league in America.