There are many that feel that the Pittsburgh Steelers really did not begin until the 1970s, but of course, that isn't true.
The origin of the Steelers dates all the way back in 1933, and they are the seventh oldest NFL franchise in existence. They made the playoffs in 1947, but that was the only time they made it to a post-season from 1933 to 1971. The Steelers would then become the power of the AFC, winning four Super Bowls in the 1970s, primarily on the strength of their potent "Steel Curtain" defense.
Their 70s success made them one of the most popular teams in the game, a status that they maintain today. Pittsburgh never had another dynasty, but they did have success winning two more Super Bowls this millennium, giving them six, which is tied with the New England Patriots for the most.
Note: Football lists are based on an amalgamation of tenure, traditional statistics, advanced statistics, playoff statistics, and post-season accolades.