On second thought I agree with Poppa San. Lambeau and Lombardi were extremely important to the Packers but what defines them is their status as the only publically owned NFL team.
According to the Packers’ website, the first stock sale took place at a meeting in 1923 where ,"… local merchants raise $5,000 by selling 1,000 shares for $5 apiece, with a stipulation that the purchaser also had to buy at least six season tickets." What a great deal!
The next stock sale in 1935 was part of a reorganization (out of receivership) and raised $15,000. In 1950 about $118,000 was raised. The shares cost $25 and according to the website, "Reportedly, one woman from a farm near Wrightstown, Wis., showed up at the team’s offices with $25 worth of quarters in a match box." In the last stock sale, about $24 million was raised in the late ‘90s for the Lambeau field renovation.
I think that’s it, no other NFL team can tell that kind of story. So I agree with Pappa San. Either the first stock sale or the collection of all four are what defines the Packers.