1975 Pittsburgh Steelers team considered the greatest in franchise history, per ESPN

On January 27, 1901, Art Rooney was born. Little did anyone know in 1933 he would be the owner and founder of the Pittsburgh Steelers franchise which would stumble throughout their early years, but when the 1970s began, there hasn't been a team as dominant as the Steelers.

Once considered the laughing stock of the league, the Steelers have turned into the most successful organization of the Super Bowl era, winning a record 6 Lombardi trophies. In that span, there have been a lot of amazing teams who have donned the black and gold. The team of the 70s won 4 Super Bowls in 6 years, and those teams were the epitome of dominant. However, teams in the early 2000s carved out their own part of the Steelers' lore by bringing home two of their own Super Bowl trophies.

With all this success, which team would be considered the best in franchise history? ESPN.com went through each NFL team and picked the best team in franchise history, and the team dubbed as the best in Steelers history was none other than the 1975 Super Bowl championship team.

See what ESPN.com had to say about their choice:

Pittsburgh Steelers
Best team: 1975

The Steelers have several candidates, but the 1975 season shines brightest among the franchise's six Super Bowl winners. This team was loaded with Hall of Famers, winning a second straight Super Bowl and framing a 1970s dynasty the game hadn't seen before. The Steelers could beat you with Terry Bradshaw's arm or Franco Harris' legs. Eight of 14 regular-season opponents scored 10 points or fewer on what became the Steel Curtain defense. In three playoff games, opposing offenses averaged 12.3 points against the Steelers. Lynn Swann had his breakout in the Super Bowl. Harris was at his best all year. Everything fell into place in this season. -- Jeremy Fowler

Not many people would argue with the selection, after all, the statistics speak for themselves, but there are other seasons and teams who deserve some credit.

1976 Steelers
I recall my father telling me this could have been the best Steelers team of the 70s, they simply had too many injuries to overcome. The defense was beyond dominant, and carried the team to the AFC Championship game. Here is a brief synopsis on the season:

The two-time defending champions got off to a rough start in 1976, losing four of their first five games. The team regrouped and, based on their powerful defense, won their last nine regular season games, five of which were shutouts. For the third consecutive year, a Steelers player (this time Jack Lambert) won the AFC Defensive Player of the Year award. Pittsburgh finished 10-4 and blew out the Colts 40-14 in the divisional playoffs. In the AFC Championship, an injury-plagued Steeler team lost 24-7 to their perennial playoff nemeses and eventual Super Bowl champions, the Raiders.

1978 Steelers
This team finished with a 14-2 record, this after a season which started under controversy. Here is a brief synopsis of the season:

The Steelers kicked off 1978 with controversy, when during a post-draft mini camp they were caught wearing shoulder pads in violation of league rules. They would lose a draft pick the following year for the infraction. Pittsburgh posted a 14-2 regular season record, best in the NFL. In the playoffs, the Steelers blew away the Denver Broncos and Houston Oilers by a combined score of 67-15 en route to Super Bowl XIII.

1979 Steelers
The 4th and final Super Bowl of the 1970s Steelers dynasty was another impressive feat. Their final record was 12-4 as they climbed the mountain for the last time until 2005 and claimed themselves the best in the NFL. Here is a brief synopsis of the season:

The 1979 season was the last season of the dynasty. Bradshaw threw for over 3,700 yards and 26 touchdowns and John Stallworth had 1183 yards receiving. The Steelers finished 12-4, once again tops in the AFC Central. In the playoffs they defeated the Dolphins 34-14 and the Oilers 27-13, to meet the Los Angeles Rams in their fourth Super Bowl.

The Rams had a number of ex-Steelers staff members, and thus knew all of their opponent's plays, audibles. and hand signs. With this knowledge, they played the Steelers hard for three quarters. Bradshaw threw three interceptions, but also had two long touchdown passes in the second half (one to Swann and one to Stallworth). The Rams couldn't recover and Pittsburgh won 31-19.

Other Steelers teams which deserve credit:

2004 Steelers

2005 Steelers

2008 Steelers