The AFL owners’ free-spending ways helped them stockpile talented players quickly. Though the new league’s early teams might not have been on par with the NFL, by the mid-1960s, that changed.

The Broncos now play in the new INVESCO Field at Mile High which opened in 2001, but for 41 seasons played on the same plot of ground on which the original AFL team performed in 1960. This, however, ...